diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/AsyncMetaTableAccessor.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/AsyncMetaTableAccessor.java
index 414d4ee7b49..813c060b520 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/AsyncMetaTableAccessor.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/AsyncMetaTableAccessor.java
@@ -101,11 +101,7 @@ public class AsyncMetaTableAccessor {
     return future;
   }
 
-  /**
-   * Returns the HRegionLocation from meta for the given region n * @param regionName region we're
-   * looking for
-   * @return HRegionLocation for the given region
-   */
+  /** Returns the HRegionLocation from meta for the given region */
   public static CompletableFuture<Optional<HRegionLocation>>
     getRegionLocation(AsyncTable<?> metaTable, byte[] regionName) {
     CompletableFuture<Optional<HRegionLocation>> future = new CompletableFuture<>();
@@ -127,11 +123,7 @@ public class AsyncMetaTableAccessor {
     return future;
   }
 
-  /**
-   * Returns the HRegionLocation from meta for the given encoded region name n * @param
-   * encodedRegionName region we're looking for
-   * @return HRegionLocation for the given region
-   */
+  /** Returns the HRegionLocation from meta for the given encoded region name */
   public static CompletableFuture<Optional<HRegionLocation>>
     getRegionLocationWithEncodedName(AsyncTable<?> metaTable, byte[] encodedRegionName) {
     CompletableFuture<Optional<HRegionLocation>> future = new CompletableFuture<>();
@@ -176,8 +168,9 @@ public class AsyncMetaTableAccessor {
   }
 
   /**
-   * Used to get all region locations for the specific table. n * @param tableName table we're
-   * looking for, can be null for getting all regions
+   * Used to get all region locations for the specific table
+   * @param metaTable scanner over meta table
+   * @param tableName table we're looking for, can be null for getting all regions
    * @return the list of region locations. The return value will be wrapped by a
    *         {@link CompletableFuture}.
    */
@@ -200,8 +193,9 @@ public class AsyncMetaTableAccessor {
   }
 
   /**
-   * Used to get table regions' info and server. n * @param tableName table we're looking for, can
-   * be null for getting all regions
+   * Used to get table regions' info and server.
+   * @param metaTable                   scanner over meta table
+   * @param tableName                   table we're looking for, can be null for getting all regions
    * @param excludeOfflinedSplitParents don't return split parents
    * @return the list of regioninfos and server. The return value will be wrapped by a
    *         {@link CompletableFuture}.
@@ -259,9 +253,11 @@ public class AsyncMetaTableAccessor {
   }
 
   /**
-   * Performs a scan of META table for given table. n * @param tableName table withing we scan
-   * @param type    scanned part of meta
-   * @param visitor Visitor invoked against each row
+   * Performs a scan of META table for given table.
+   * @param metaTable scanner over meta table
+   * @param tableName table within we scan
+   * @param type      scanned part of meta
+   * @param visitor   Visitor invoked against each row
    */
   private static CompletableFuture<Void> scanMeta(AsyncTable<AdvancedScanResultConsumer> metaTable,
     TableName tableName, QueryType type, final Visitor visitor) {
@@ -270,11 +266,13 @@ public class AsyncMetaTableAccessor {
   }
 
   /**
-   * Performs a scan of META table for given table. n * @param startRow Where to start the scan
-   * @param stopRow Where to stop the scan
-   * @param type    scanned part of meta
-   * @param maxRows maximum rows to return
-   * @param visitor Visitor invoked against each row
+   * Performs a scan of META table for given table.
+   * @param metaTable scanner over meta table
+   * @param startRow  Where to start the scan
+   * @param stopRow   Where to stop the scan
+   * @param type      scanned part of meta
+   * @param maxRows   maximum rows to return
+   * @param visitor   Visitor invoked against each row
    */
   private static CompletableFuture<Void> scanMeta(AsyncTable<AdvancedScanResultConsumer> metaTable,
     byte[] startRow, byte[] stopRow, QueryType type, int maxRows, final Visitor visitor) {
@@ -410,9 +408,13 @@ public class AsyncMetaTableAccessor {
    *         can't deserialize the result.
    */
   private static Optional<RegionLocations> getRegionLocations(final Result r) {
-    if (r == null) return Optional.empty();
+    if (r == null) {
+      return Optional.empty();
+    }
     Optional<RegionInfo> regionInfo = getHRegionInfo(r, getRegionInfoColumn());
-    if (!regionInfo.isPresent()) return Optional.empty();
+    if (!regionInfo.isPresent()) {
+      return Optional.empty();
+    }
 
     List<HRegionLocation> locations = new ArrayList<HRegionLocation>(1);
     NavigableMap<byte[], NavigableMap<byte[], byte[]>> familyMap = r.getNoVersionMap();
@@ -420,15 +422,18 @@ public class AsyncMetaTableAccessor {
     locations.add(getRegionLocation(r, regionInfo.get(), 0));
 
     NavigableMap<byte[], byte[]> infoMap = familyMap.get(getCatalogFamily());
-    if (infoMap == null) return Optional.of(new RegionLocations(locations));
+    if (infoMap == null) {
+      return Optional.of(new RegionLocations(locations));
+    }
 
     // iterate until all serverName columns are seen
     int replicaId = 0;
     byte[] serverColumn = getServerColumn(replicaId);
-    SortedMap<byte[], byte[]> serverMap = null;
-    serverMap = infoMap.tailMap(serverColumn, false);
+    SortedMap<byte[], byte[]> serverMap = infoMap.tailMap(serverColumn, false);
 
-    if (serverMap.isEmpty()) return Optional.of(new RegionLocations(locations));
+    if (serverMap.isEmpty()) {
+      return Optional.of(new RegionLocations(locations));
+    }
 
     for (Map.Entry<byte[], byte[]> entry : serverMap.entrySet()) {
       replicaId = parseReplicaIdFromServerColumn(entry.getKey());
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterId.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterId.java
index 9b7a5de19bd..8c675c4522e 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterId.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterId.java
@@ -51,6 +51,7 @@ public class ClusterId {
   }
 
   /**
+   * Parse the serialized representation of the {@link ClusterId}
    * @param bytes A pb serialized {@link ClusterId} instance with pb magic prefix
    * @return An instance of {@link ClusterId} made from <code>bytes</code> n * @see #toByteArray()
    */
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterMetricsBuilder.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterMetricsBuilder.java
index 7ef8a208611..630e3620a67 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterMetricsBuilder.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterMetricsBuilder.java
@@ -67,11 +67,11 @@ public final class ClusterMetricsBuilder {
           .collect(Collectors.toList()))
         .addAllTableRegionStatesCount(metrics.getTableRegionStatesCount().entrySet().stream()
           .map(status -> ClusterStatusProtos.TableRegionStatesCount.newBuilder()
-            .setTableName(ProtobufUtil.toProtoTableName((status.getKey())))
+            .setTableName(ProtobufUtil.toProtoTableName(status.getKey()))
             .setRegionStatesCount(ProtobufUtil.toTableRegionStatesCount(status.getValue())).build())
           .collect(Collectors.toList()));
     if (metrics.getMasterName() != null) {
-      builder.setMaster(ProtobufUtil.toServerName((metrics.getMasterName())));
+      builder.setMaster(ProtobufUtil.toServerName(metrics.getMasterName()));
     }
     if (metrics.getMasterTasks() != null) {
       builder.addAllMasterTasks(metrics.getMasterTasks().stream()
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterStatus.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterStatus.java
index e218437694b..e3b1a8ab662 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterStatus.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterStatus.java
@@ -186,6 +186,7 @@ public class ClusterStatus implements ClusterMetrics {
   }
 
   /** Returns the HBase version string as reported by the HMaster */
+  @Override
   public String getHBaseVersion() {
     return metrics.getHBaseVersion();
   }
@@ -279,6 +280,7 @@ public class ClusterStatus implements ClusterMetrics {
     return serverMetrics == null ? null : new ServerLoad(serverMetrics);
   }
 
+  @Override
   public String getClusterId() {
     return metrics.getClusterId();
   }
@@ -289,6 +291,7 @@ public class ClusterStatus implements ClusterMetrics {
   }
 
   /**
+   * Get the list of master coprocessor names.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link #getMasterCoprocessorNames} instead.
    */
@@ -299,6 +302,7 @@ public class ClusterStatus implements ClusterMetrics {
   }
 
   /**
+   * Get the last major compaction time for a given table.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link #getLastMajorCompactionTimestamp(TableName)} instead.
    */
@@ -308,6 +312,7 @@ public class ClusterStatus implements ClusterMetrics {
   }
 
   /**
+   * Get the last major compaction time for a given region.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link #getLastMajorCompactionTimestamp(byte[])} instead.
    */
@@ -317,6 +322,7 @@ public class ClusterStatus implements ClusterMetrics {
   }
 
   /**
+   * Returns true if the balancer is enabled.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 No flag in 2.0
    */
   @Deprecated
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/CoprocessorEnvironment.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/CoprocessorEnvironment.java
index 94909f1c14e..32e06d61024 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/CoprocessorEnvironment.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/CoprocessorEnvironment.java
@@ -44,8 +44,8 @@ public interface CoprocessorEnvironment<C extends Coprocessor> {
   int getLoadSequence();
 
   /**
-   * @return a Read-only Configuration; throws {@link UnsupportedOperationException} if you try to
-   *         set a configuration.
+   * Returns a Read-only Configuration; throws {@link UnsupportedOperationException} if you try to
+   * set a configuration.
    */
   Configuration getConfiguration();
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/HBaseServerException.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/HBaseServerException.java
index 3484995c1bf..47a86f9492f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/HBaseServerException.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/HBaseServerException.java
@@ -44,10 +44,7 @@ public class HBaseServerException extends HBaseIOException {
     this.serverOverloaded = serverOverloaded;
   }
 
-  /**
-   * @param t throwable to check for server overloaded state
-   * @return True if the server was considered overloaded when the exception was thrown
-   */
+  /** Returns True if the server was considered overloaded when the exception was thrown */
   public static boolean isServerOverloaded(Throwable t) {
     if (t instanceof HBaseServerException) {
       return ((HBaseServerException) t).isServerOverloaded();
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java
index d55b417d482..43640858ccc 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java
@@ -176,6 +176,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Check if a given family name is allowed.
    * @param b Family name.
    * @return <code>b</code>
    * @throws IllegalArgumentException If not null and not a legitimate family name: i.e. 'printable'
@@ -205,19 +206,12 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
     return delegatee.getNameAsString();
   }
 
-  /**
-   * @param key The key.
-   * @return The value.
-   */
   @Override
   public byte[] getValue(byte[] key) {
     return delegatee.getValue(key);
   }
 
-  /**
-   * @param key The key.
-   * @return The value as a string.
-   */
+  @Override
   public String getValue(String key) {
     byte[] value = getValue(Bytes.toBytes(key));
     return value == null ? null : Bytes.toString(value);
@@ -228,35 +222,22 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
     return delegatee.getValues();
   }
 
-  /**
-   * @param key   The key.
-   * @param value The value.
-   * @return this (for chained invocation)
-   */
   public HColumnDescriptor setValue(byte[] key, byte[] value) {
     getDelegateeForModification().setValue(key, value);
     return this;
   }
 
-  /**
-   * @param key Key whose key and value we're to remove from HCD parameters.
-   */
   public void remove(final byte[] key) {
     getDelegateeForModification().removeValue(new Bytes(key));
   }
 
-  /**
-   * @param key   The key.
-   * @param value The value.
-   * @return this (for chained invocation)
-   */
   public HColumnDescriptor setValue(String key, String value) {
     getDelegateeForModification().setValue(key, value);
     return this;
   }
 
   /**
-   * @return compression type being used for the column family
+   * Returns compression type being used for the column family
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0
    *             (<a href="https://issues.apache.org/jira/browse/HBASE-13655">HBASE-13655</a>). Use
    *             {@link #getCompressionType()}.
@@ -267,7 +248,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
-   * @return compression type being used for the column family for major compaction
+   * Returns compression type being used for the column family for major compaction
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0
    *             (<a href="https://issues.apache.org/jira/browse/HBASE-13655">HBASE-13655</a>). Use
    *             {@link #getCompactionCompressionType()}.
@@ -283,6 +264,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set maximum versions to keep
    * @param value maximum number of versions
    * @return this (for chained invocation)
    */
@@ -320,6 +302,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set block size to use when writing
    * @param value Blocksize to use when writing out storefiles/hfiles on this column family.
    * @return this (for chained invocation)
    */
@@ -423,6 +406,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set or clear the in memory flag.
    * @param value True if we are to favor keeping all values for this column family in the
    *              HRegionServer cache
    * @return this (for chained invocation)
@@ -438,6 +422,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set the in memory compaction policy.
    * @param value the prefered in-memory compaction policy for this column family
    * @return this (for chained invocation)
    */
@@ -452,6 +437,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set the keep deleted cells policy.
    * @param value True if deleted rows should not be collected immediately.
    * @return this (for chained invocation)
    */
@@ -481,6 +467,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set the time to live of cell contents
    * @param value Time-to-live of cell contents, in seconds.
    * @return this (for chained invocation)
    */
@@ -490,6 +477,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set the time to live of cell contents
    * @param value Time to live of cell contents, in human readable format
    * @see org.apache.hadoop.hbase.util.PrettyPrinter#format(String, Unit)
    * @return this (for chained invocation)
@@ -505,6 +493,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set the minimum number of versions to keep.
    * @param value The minimum number of versions to keep. (used when timeToLive is set)
    * @return this (for chained invocation)
    */
@@ -519,6 +508,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set or clear the block cache enabled flag.
    * @param value True if hfile DATA type blocks should be cached (We always cache INDEX and BLOOM
    *              blocks; you cannot turn this off).
    * @return this (for chained invocation)
@@ -534,6 +524,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set the bloom filter type.
    * @param value bloom filter type
    * @return this (for chained invocation)
    */
@@ -547,10 +538,6 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
     return delegatee.getScope();
   }
 
-  /**
-   * @param value the scope tag
-   * @return this (for chained invocation)
-   */
   public HColumnDescriptor setScope(int value) {
     getDelegateeForModification().setScope(value);
     return this;
@@ -562,6 +549,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set or clear the cache data on write flag.
    * @param value true if we should cache data blocks on write
    * @return this (for chained invocation)
    */
@@ -571,7 +559,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
-   * This is a noop call from HBase 2.0 onwards
+   * Set or clear the cache in L1 flag. This is a noop call from HBase 2.0 onwards
    * @return this (for chained invocation)
    * @deprecated Since 2.0 and will be removed in 3.0 with out any replacement. Caching data in on
    *             heap Cache, when there are both on heap LRU Cache and Bucket Cache will no longer
@@ -588,6 +576,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set or clear the cache indexes on write flag.
    * @param value true if we should cache index blocks on write
    * @return this (for chained invocation)
    */
@@ -602,6 +591,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set or clear the cache bloom filters on write flag.
    * @param value true if we should cache bloomfilter blocks on write
    * @return this (for chained invocation)
    */
@@ -616,6 +606,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set or clear the evict bloom filters on close flag.
    * @param value true if we should evict cached blocks from the blockcache on close
    * @return this (for chained invocation)
    */
@@ -630,6 +621,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Set or clear the prefetch on open flag.
    * @param value true if we should prefetch blocks into the blockcache on open
    * @return this (for chained invocation)
    */
@@ -638,9 +630,6 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
     return this;
   }
 
-  /**
-   * @see java.lang.Object#toString()
-   */
   @Override
   public String toString() {
     return delegatee.toString();
@@ -660,9 +649,6 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
     return ColumnFamilyDescriptorBuilder.getDefaultValues();
   }
 
-  /**
-   * @see java.lang.Object#equals(java.lang.Object)
-   */
   @Override
   public boolean equals(Object obj) {
     if (this == obj) {
@@ -674,9 +660,6 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
     return false;
   }
 
-  /**
-   * @see java.lang.Object#hashCode()
-   */
   @Override
   public int hashCode() {
     return delegatee.hashCode();
@@ -688,7 +671,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
-   * @return This instance serialized with pb with pb magic prefix
+   * Returns This instance serialized with pb with pb magic prefix
    * @see #parseFrom(byte[])
    */
   public byte[] toByteArray() {
@@ -696,6 +679,7 @@ public class HColumnDescriptor implements ColumnFamilyDescriptor, Comparable<HCo
   }
 
   /**
+   * Parse a serialized representation of a {@link HColumnDescriptor}
    * @param bytes A pb serialized {@link HColumnDescriptor} instance with pb magic prefix
    * @return An instance of {@link HColumnDescriptor} made from <code>bytes</code> n * @see
    *         #toByteArray()
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionInfo.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionInfo.java
index 5e9abd31a7e..2f4d6377888 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionInfo.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionInfo.java
@@ -221,7 +221,7 @@ public class HRegionInfo implements RegionInfo {
 
   /**
    * Construct HRegionInfo with explicit parameters
-   * @param tableName the table descriptor
+   * @param tableName the table name
    * @param startKey  first key in region
    * @param endKey    end of key range
    * @param split     true if this region has split and we have daughter regions regions that may or
@@ -234,37 +234,37 @@ public class HRegionInfo implements RegionInfo {
 
   /**
    * Construct HRegionInfo with explicit parameters
-   * @param tableName the table descriptor
+   * @param tableName the table name
    * @param startKey  first key in region
    * @param endKey    end of key range
    * @param split     true if this region has split and we have daughter regions regions that may or
    *                  may not hold references to this region.
-   * @param regionid  Region id to use. n
+   * @param regionId  Region id to use.
    */
   public HRegionInfo(final TableName tableName, final byte[] startKey, final byte[] endKey,
-    final boolean split, final long regionid) throws IllegalArgumentException {
-    this(tableName, startKey, endKey, split, regionid, DEFAULT_REPLICA_ID);
+    final boolean split, final long regionId) throws IllegalArgumentException {
+    this(tableName, startKey, endKey, split, regionId, DEFAULT_REPLICA_ID);
   }
 
   /**
    * Construct HRegionInfo with explicit parameters
-   * @param tableName the table descriptor
+   * @param tableName the table name
    * @param startKey  first key in region
    * @param endKey    end of key range
    * @param split     true if this region has split and we have daughter regions regions that may or
    *                  may not hold references to this region.
-   * @param regionid  Region id to use.
-   * @param replicaId the replicaId to use n
+   * @param regionId  Region id to use.
+   * @param replicaId the replicaId to use
    */
   public HRegionInfo(final TableName tableName, final byte[] startKey, final byte[] endKey,
-    final boolean split, final long regionid, final int replicaId) throws IllegalArgumentException {
+    final boolean split, final long regionId, final int replicaId) throws IllegalArgumentException {
     super();
     if (tableName == null) {
       throw new IllegalArgumentException("TableName cannot be null");
     }
     this.tableName = tableName;
     this.offLine = false;
-    this.regionId = regionid;
+    this.regionId = regionId;
     this.replicaId = replicaId;
     if (this.replicaId > MAX_REPLICA_ID) {
       throw new IllegalArgumentException("ReplicaId cannot be greater than" + MAX_REPLICA_ID);
@@ -280,7 +280,7 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
-   * Costruct a copy of another HRegionInfo n
+   * Construct a copy of another HRegionInfo
    */
   public HRegionInfo(RegionInfo other) {
     super();
@@ -303,8 +303,10 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
-   * Make a region name of passed parameters. n * @param startKey Can be null
-   * @param regionid  Region id (Usually timestamp from when region was created).
+   * Make a region name of passed parameters.
+   * @param tableName the table name
+   * @param startKey  Can be null
+   * @param regionId  Region id (Usually timestamp from when region was created).
    * @param newFormat should we create the region name in the new format (such that it contains its
    *                  encoded name?).
    * @return Region name made of passed tableName, startKey and id
@@ -314,12 +316,14 @@ public class HRegionInfo implements RegionInfo {
   @Deprecated
   @InterfaceAudience.Private
   public static byte[] createRegionName(final TableName tableName, final byte[] startKey,
-    final long regionid, boolean newFormat) {
-    return RegionInfo.createRegionName(tableName, startKey, Long.toString(regionid), newFormat);
+    final long regionId, boolean newFormat) {
+    return RegionInfo.createRegionName(tableName, startKey, Long.toString(regionId), newFormat);
   }
 
   /**
-   * Make a region name of passed parameters. n * @param startKey Can be null
+   * Make a region name of passed parameters.
+   * @param tableName the table name
+   * @param startKey  Can be null
    * @param id        Region id (Usually timestamp from when region was created).
    * @param newFormat should we create the region name in the new format (such that it contains its
    *                  encoded name?).
@@ -335,10 +339,12 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
-   * Make a region name of passed parameters. n * @param startKey Can be null
-   * @param regionid Region id (Usually timestamp from when region was created). n * @param
-   *                 newFormat should we create the region name in the new format (such that it
-   *                 contains its encoded name?).
+   * Make a region name of passed parameters.
+   * @param tableName the table name
+   * @param startKey  Can be null
+   * @param regionId  Region id (Usually timestamp from when region was created).
+   * @param newFormat should we create the region name in the new format (such that it contains its
+   *                  encoded name?).
    * @return Region name made of passed tableName, startKey, id and replicaId
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link RegionInfo#createRegionName(TableName, byte[], long, int, boolean)}.
@@ -346,13 +352,15 @@ public class HRegionInfo implements RegionInfo {
   @Deprecated
   @InterfaceAudience.Private
   public static byte[] createRegionName(final TableName tableName, final byte[] startKey,
-    final long regionid, int replicaId, boolean newFormat) {
-    return RegionInfo.createRegionName(tableName, startKey, Bytes.toBytes(Long.toString(regionid)),
+    final long regionId, int replicaId, boolean newFormat) {
+    return RegionInfo.createRegionName(tableName, startKey, Bytes.toBytes(Long.toString(regionId)),
       replicaId, newFormat);
   }
 
   /**
-   * Make a region name of passed parameters. n * @param startKey Can be null
+   * Make a region name of passed parameters.
+   * @param tableName the table name
+   * @param startKey  Can be null
    * @param id        Region id (Usually timestamp from when region was created).
    * @param newFormat should we create the region name in the new format (such that it contains its
    *                  encoded name?).
@@ -368,9 +376,11 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
-   * Make a region name of passed parameters. n * @param startKey Can be null
-   * @param id Region id (Usually timestamp from when region was created). n * @param newFormat
-   *           should we create the region name in the new format
+   * Make a region name of passed parameters.
+   * @param tableName the table name
+   * @param startKey  Can be null
+   * @param id        Region id (Usually timestamp from when region was created)
+   * @param newFormat should we create the region name in the new format
    * @return Region name made of passed tableName, startKey, id and replicaId
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link RegionInfo#createRegionName(TableName, byte[], byte[], int, boolean)}.
@@ -546,6 +556,7 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
+   * Set or clear the split status flag.
    * @param split set split status
    */
   public void setSplit(boolean split) {
@@ -684,6 +695,7 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
+   * Serialize a {@link HRegionInfo} into a byte array.
    * @return This instance serialized as protobuf w/ a magic pb prefix.
    * @see #parseFrom(byte[])
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
@@ -695,6 +707,7 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
+   * Parse a serialized representation of a {@link HRegionInfo}.
    * @return A deserialized {@link HRegionInfo} or null if we failed deserialize or passed bytes
    *         null
    * @see #toByteArray()
@@ -708,6 +721,7 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
+   * Parse a serialized representation of a {@link HRegionInfo}.
    * @return A deserialized {@link HRegionInfo} or null if we failed deserialize or passed bytes
    *         null
    * @see #toByteArray()
@@ -725,6 +739,7 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
+   * Parse a serialized representation of a {@link HRegionInfo}.
    * @param bytes A pb RegionInfo serialized with a pb magic prefix.
    * @return A deserialized {@link HRegionInfo} n * @see #toByteArray()
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
@@ -736,6 +751,7 @@ public class HRegionInfo implements RegionInfo {
   }
 
   /**
+   * Parse a serialized representation of a {@link HRegionInfo}.
    * @param bytes  A pb RegionInfo serialized with a pb magic prefix.
    * @param offset starting point in the byte array
    * @param len    length to read on the byte array
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionLocation.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionLocation.java
index 6ae93bb3954..a7720b2734e 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionLocation.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/HRegionLocation.java
@@ -110,8 +110,8 @@ public class HRegionLocation implements Comparable<HRegionLocation> {
   }
 
   /**
-   * @return String made of hostname and port formatted as per
-   *         {@link Addressing#createHostAndPortStr(String, int)}
+   * Returns String made of hostname and port formatted as per
+   * {@link Addressing#createHostAndPortStr(String, int)}
    */
   public String getHostnamePort() {
     return Addressing.createHostAndPortStr(this.getHostname(), this.getPort());
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java
index 6c8ea810d03..f5448e61737 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java
@@ -801,6 +801,7 @@ public class HTableDescriptor implements TableDescriptor, Comparable<HTableDescr
     new HTableDescriptor(TableDescriptorBuilder.NAMESPACE_TABLEDESC);
 
   /**
+   * Set the table owner.
    * @deprecated since 0.94.1
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-6188">HBASE-6188</a>
    */
@@ -811,6 +812,7 @@ public class HTableDescriptor implements TableDescriptor, Comparable<HTableDescr
   }
 
   /**
+   * Set the table owner.
    * @deprecated since 0.94.1
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-6188">HBASE-6188</a>
    */
@@ -822,6 +824,7 @@ public class HTableDescriptor implements TableDescriptor, Comparable<HTableDescr
   }
 
   /**
+   * Get the table owner.
    * @deprecated since 0.94.1
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-6188">HBASE-6188</a>
    */
@@ -832,14 +835,14 @@ public class HTableDescriptor implements TableDescriptor, Comparable<HTableDescr
   }
 
   /**
-   * @return This instance serialized with pb with pb magic prefix
-   * @see #parseFrom(byte[])
+   * Returns This instance serialized with pb with pb magic prefix
    */
   public byte[] toByteArray() {
     return TableDescriptorBuilder.toByteArray(delegatee);
   }
 
   /**
+   * Parse the serialized representation of a {@link HTableDescriptor}
    * @param bytes A pb serialized {@link HTableDescriptor} instance with pb magic prefix
    * @return An instance of {@link HTableDescriptor} made from <code>bytes</code> nn * @see
    *         #toByteArray()
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/MetaTableAccessor.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/MetaTableAccessor.java
index 01b5f49a205..48476e4bb3a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/MetaTableAccessor.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/MetaTableAccessor.java
@@ -38,7 +38,6 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.hbase.Cell.Type;
 import org.apache.hadoop.hbase.client.Connection;
 import org.apache.hadoop.hbase.client.Consistency;
 import org.apache.hadoop.hbase.client.Delete;
@@ -155,6 +154,7 @@ public class MetaTableAccessor {
   private static final byte SEPARATED_BYTE = 0x00;
 
   @InterfaceAudience.Private
+  @SuppressWarnings("ImmutableEnumChecker")
   public enum QueryType {
     ALL(HConstants.TABLE_FAMILY, HConstants.CATALOG_FAMILY),
     REGION(HConstants.CATALOG_FAMILY),
@@ -364,8 +364,8 @@ public class MetaTableAccessor {
   }
 
   /**
-   * @return Return all regioninfos listed in the 'info:merge*' columns of the
-   *         <code>regionName</code> row.
+   * Returns Return all regioninfos listed in the 'info:merge*' columns of the
+   * <code>regionName</code> row.
    */
   @Nullable
   public static List<RegionInfo> getMergeRegions(Connection connection, byte[] regionName)
@@ -381,8 +381,8 @@ public class MetaTableAccessor {
   }
 
   /**
-   * @return Deserialized values of &lt;qualifier,regioninfo&gt; pairs taken from column values that
-   *         match the regex 'info:merge.*' in array of <code>cells</code>.
+   * Returns Deserialized values of &lt;qualifier,regioninfo&gt; pairs taken from column values that
+   * match the regex 'info:merge.*' in array of <code>cells</code>.
    */
   @Nullable
   public static Map<String, RegionInfo> getMergeRegionsWithName(Cell[] cells) {
@@ -408,8 +408,8 @@ public class MetaTableAccessor {
   }
 
   /**
-   * @return Deserialized regioninfo values taken from column values that match the regex
-   *         'info:merge.*' in array of <code>cells</code>.
+   * Returns Deserialized regioninfo values taken from column values that match the regex
+   * 'info:merge.*' in array of <code>cells</code>.
    */
   @Nullable
   public static List<RegionInfo> getMergeRegions(Cell[] cells) {
@@ -418,8 +418,8 @@ public class MetaTableAccessor {
   }
 
   /**
-   * @return True if any merge regions present in <code>cells</code>; i.e. the column in
-   *         <code>cell</code> matches the regex 'info:merge.*'.
+   * Returns True if any merge regions present in <code>cells</code>; i.e. the column in
+   * <code>cell</code> matches the regex 'info:merge.*'.
    */
   public static boolean hasMergeRegions(Cell[] cells) {
     for (Cell cell : cells) {
@@ -483,6 +483,7 @@ public class MetaTableAccessor {
     return getListOfRegionInfos(result);
   }
 
+  @SuppressWarnings("MixedMutabilityReturnType")
   private static List<RegionInfo>
     getListOfRegionInfos(final List<Pair<RegionInfo, ServerName>> pairs) {
     if (pairs == null || pairs.isEmpty()) {
@@ -496,8 +497,7 @@ public class MetaTableAccessor {
   }
 
   /**
-   * @param tableName table we're working with
-   * @return start row for scanning META according to query type
+   * Returns start row for scanning META according to query type
    */
   public static byte[] getTableStartRowForMeta(TableName tableName, QueryType type) {
     if (tableName == null) {
@@ -518,8 +518,7 @@ public class MetaTableAccessor {
   }
 
   /**
-   * @param tableName table we're working with
-   * @return stop row for scanning META according to query type
+   * Returns stop row for scanning META according to query type
    */
   public static byte[] getTableStopRowForMeta(TableName tableName, QueryType type) {
     if (tableName == null) {
@@ -641,9 +640,10 @@ public class MetaTableAccessor {
   }
 
   /**
+   * Get the user regions a given server is hosting.
    * @param connection connection we're using
    * @param serverName server whose regions we're interested in
-   * @return List of user regions installed on this server (does not include catalog regions). n
+   * @return List of user regions installed on this server (does not include catalog regions).
    */
   public static NavigableMap<RegionInfo, Result> getServerUserRegions(Connection connection,
     final ServerName serverName) throws IOException {
@@ -1284,7 +1284,7 @@ public class MetaTableAccessor {
       if (info == null) {
         return true;
       }
-      if (!(info.getTable().equals(tableName))) {
+      if (!info.getTable().equals(tableName)) {
         return false;
       }
       return super.visit(rowResult);
@@ -1321,14 +1321,14 @@ public class MetaTableAccessor {
     if (splitA != null) {
       put.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(put.getRow())
         .setFamily(HConstants.CATALOG_FAMILY).setQualifier(HConstants.SPLITA_QUALIFIER)
-        .setTimestamp(put.getTimestamp()).setType(Type.Put).setValue(RegionInfo.toByteArray(splitA))
-        .build());
+        .setTimestamp(put.getTimestamp()).setType(Cell.Type.Put)
+        .setValue(RegionInfo.toByteArray(splitA)).build());
     }
     if (splitB != null) {
       put.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(put.getRow())
         .setFamily(HConstants.CATALOG_FAMILY).setQualifier(HConstants.SPLITB_QUALIFIER)
-        .setTimestamp(put.getTimestamp()).setType(Type.Put).setValue(RegionInfo.toByteArray(splitB))
-        .build());
+        .setTimestamp(put.getTimestamp()).setType(Cell.Type.Put)
+        .setValue(RegionInfo.toByteArray(splitB)).build());
     }
     return put;
   }
@@ -1509,8 +1509,8 @@ public class MetaTableAccessor {
       String qualifier = String.format(HConstants.MERGE_QUALIFIER_PREFIX_STR + "%04d", counter++);
       put.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(put.getRow())
         .setFamily(HConstants.CATALOG_FAMILY).setQualifier(Bytes.toBytes(qualifier))
-        .setTimestamp(put.getTimestamp()).setType(Type.Put).setValue(RegionInfo.toByteArray(ri))
-        .build());
+        .setTimestamp(put.getTimestamp()).setType(Cell.Type.Put)
+        .setValue(RegionInfo.toByteArray(ri)).build());
     }
     return put;
   }
@@ -1852,7 +1852,7 @@ public class MetaTableAccessor {
   public static Put addRegionInfo(final Put p, final RegionInfo hri) throws IOException {
     p.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(p.getRow())
       .setFamily(getCatalogFamily()).setQualifier(HConstants.REGIONINFO_QUALIFIER)
-      .setTimestamp(p.getTimestamp()).setType(Type.Put)
+      .setTimestamp(p.getTimestamp()).setType(Cell.Type.Put)
       // Serialize the Default Replica HRI otherwise scan of hbase:meta
       // shows an info:regioninfo value with encoded name and region
       // name that differs from that of the hbase;meta row.
@@ -1872,8 +1872,8 @@ public class MetaTableAccessor {
         .setQualifier(getStartCodeColumn(replicaId)).setTimestamp(p.getTimestamp())
         .setType(Cell.Type.Put).setValue(Bytes.toBytes(sn.getStartcode())).build())
       .add(builder.clear().setRow(p.getRow()).setFamily(getCatalogFamily())
-        .setQualifier(getSeqNumColumn(replicaId)).setTimestamp(p.getTimestamp()).setType(Type.Put)
-        .setValue(Bytes.toBytes(openSeqNum)).build());
+        .setQualifier(getSeqNumColumn(replicaId)).setTimestamp(p.getTimestamp())
+        .setType(Cell.Type.Put).setValue(Bytes.toBytes(openSeqNum)).build());
   }
 
   private static void writeRegionName(ByteArrayOutputStream out, byte[] regionName) {
@@ -1922,7 +1922,7 @@ public class MetaTableAccessor {
     byte[] value = getParentsBytes(parents);
     put.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(put.getRow())
       .setFamily(HConstants.REPLICATION_BARRIER_FAMILY).setQualifier(REPLICATION_PARENT_QUALIFIER)
-      .setTimestamp(put.getTimestamp()).setType(Type.Put).setValue(value).build());
+      .setTimestamp(put.getTimestamp()).setType(Cell.Type.Put).setValue(value).build());
   }
 
   public static Put makePutForReplicationBarrier(RegionInfo regionInfo, long openSeqNum, long ts)
@@ -1938,7 +1938,7 @@ public class MetaTableAccessor {
   public static void addReplicationBarrier(Put put, long openSeqNum) throws IOException {
     put.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(put.getRow())
       .setFamily(HConstants.REPLICATION_BARRIER_FAMILY).setQualifier(HConstants.SEQNUM_QUALIFIER)
-      .setTimestamp(put.getTimestamp()).setType(Type.Put).setValue(Bytes.toBytes(openSeqNum))
+      .setTimestamp(put.getTimestamp()).setType(Cell.Type.Put).setValue(Bytes.toBytes(openSeqNum))
       .build());
   }
 
@@ -1946,8 +1946,8 @@ public class MetaTableAccessor {
     CellBuilder builder = CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY);
     return p
       .add(builder.clear().setRow(p.getRow()).setFamily(getCatalogFamily())
-        .setQualifier(getServerColumn(replicaId)).setTimestamp(p.getTimestamp()).setType(Type.Put)
-        .build())
+        .setQualifier(getServerColumn(replicaId)).setTimestamp(p.getTimestamp())
+        .setType(Cell.Type.Put).build())
       .add(builder.clear().setRow(p.getRow()).setFamily(getCatalogFamily())
         .setQualifier(getStartCodeColumn(replicaId)).setTimestamp(p.getTimestamp())
         .setType(Cell.Type.Put).build())
@@ -2096,7 +2096,7 @@ public class MetaTableAccessor {
   private static Put addSequenceNum(Put p, long openSeqNum, int replicaId) throws IOException {
     return p.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(p.getRow())
       .setFamily(HConstants.CATALOG_FAMILY).setQualifier(getSeqNumColumn(replicaId))
-      .setTimestamp(p.getTimestamp()).setType(Type.Put).setValue(Bytes.toBytes(openSeqNum))
+      .setTimestamp(p.getTimestamp()).setType(Cell.Type.Put).setValue(Bytes.toBytes(openSeqNum))
       .build());
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLoad.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLoad.java
index 0a762bf78a6..b45171e6495 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLoad.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLoad.java
@@ -354,6 +354,7 @@ public class RegionLoad implements RegionMetrics {
   }
 
   /** Returns the reference count for the stores of this region */
+  @Override
   public int getStoreRefCount() {
     return metrics.getStoreRefCount();
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLocations.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLocations.java
index 4d6dd6d43fa..4c0390c6c3b 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLocations.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLocations.java
@@ -208,6 +208,7 @@ public class RegionLocations implements Iterable<HRegionLocation> {
    * @param other the locations to merge with
    * @return an RegionLocations object with merged locations or the same object if nothing is merged
    */
+  @SuppressWarnings("ReferenceEquality")
   public RegionLocations mergeLocations(RegionLocations other) {
     assert other != null;
 
@@ -280,6 +281,7 @@ public class RegionLocations implements Iterable<HRegionLocation> {
    * @return an RegionLocations object with updated locations or the same object if nothing is
    *         updated
    */
+  @SuppressWarnings("ReferenceEquality")
   public RegionLocations updateLocation(HRegionLocation location, boolean checkForEquals,
     boolean force) {
     assert location != null;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionMetrics.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionMetrics.java
index 645a31a8552..d915e7a32ca 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionMetrics.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/RegionMetrics.java
@@ -107,8 +107,8 @@ public interface RegionMetrics {
   int getStoreRefCount();
 
   /**
-   * @return the max reference count for any store file among all compacted stores files of this
-   *         region
+   * Returns the max reference count for any store file among all compacted stores files of this
+   * region
    */
   int getMaxCompactedStoreFileRefCount();
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerLoad.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerLoad.java
index 2320c8e908e..714a1412553 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerLoad.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerLoad.java
@@ -79,16 +79,17 @@ public class ServerLoad implements ServerMetrics {
     for (RegionMetrics rl : metrics.getRegionMetrics().values()) {
       stores += rl.getStoreCount();
       storefiles += rl.getStoreFileCount();
-      storeUncompressedSizeMB += rl.getUncompressedStoreFileSize().get(Size.Unit.MEGABYTE);
-      storefileSizeMB += rl.getStoreFileSize().get(Size.Unit.MEGABYTE);
-      memstoreSizeMB += rl.getMemStoreSize().get(Size.Unit.MEGABYTE);
+      storeUncompressedSizeMB += (int) rl.getUncompressedStoreFileSize().get(Size.Unit.MEGABYTE);
+      storefileSizeMB += (int) rl.getStoreFileSize().get(Size.Unit.MEGABYTE);
+      memstoreSizeMB += (int) rl.getMemStoreSize().get(Size.Unit.MEGABYTE);
       readRequestsCount += rl.getReadRequestCount();
       filteredReadRequestsCount += rl.getFilteredReadRequestCount();
       writeRequestsCount += rl.getWriteRequestCount();
-      storefileIndexSizeKB += rl.getStoreFileIndexSize().get(Size.Unit.KILOBYTE);
-      rootIndexSizeKB += rl.getStoreFileRootLevelIndexSize().get(Size.Unit.KILOBYTE);
-      totalStaticIndexSizeKB += rl.getStoreFileUncompressedDataIndexSize().get(Size.Unit.KILOBYTE);
-      totalStaticBloomSizeKB += rl.getBloomFilterSize().get(Size.Unit.KILOBYTE);
+      storefileIndexSizeKB += (long) rl.getStoreFileIndexSize().get(Size.Unit.KILOBYTE);
+      rootIndexSizeKB += (int) rl.getStoreFileRootLevelIndexSize().get(Size.Unit.KILOBYTE);
+      totalStaticIndexSizeKB +=
+        (int) rl.getStoreFileUncompressedDataIndexSize().get(Size.Unit.KILOBYTE);
+      totalStaticBloomSizeKB += (int) rl.getBloomFilterSize().get(Size.Unit.KILOBYTE);
       totalCompactingKVs += rl.getCompactingCellCount();
       currentCompactedKVs += rl.getCompactedCellCount();
     }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerMetricsBuilder.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerMetricsBuilder.java
index 72f78220c1a..1e57857db69 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerMetricsBuilder.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ServerMetricsBuilder.java
@@ -44,10 +44,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos;
 @InterfaceAudience.Private
 public final class ServerMetricsBuilder {
 
-  /**
-   * @param sn the server name
-   * @return a empty metrics
-   */
   public static ServerMetrics of(ServerName sn) {
     return newBuilder(sn).build();
   }
@@ -280,6 +276,7 @@ public final class ServerMetricsBuilder {
       return versionNumber;
     }
 
+    @Override
     public String getVersion() {
       return version;
     }
@@ -383,15 +380,17 @@ public final class ServerMetricsBuilder {
         int currentMaxCompactedStoreFileRefCount = r.getMaxCompactedStoreFileRefCount();
         maxCompactedStoreFileRefCount =
           Math.max(maxCompactedStoreFileRefCount, currentMaxCompactedStoreFileRefCount);
-        uncompressedStoreFileSizeMB += r.getUncompressedStoreFileSize().get(Size.Unit.MEGABYTE);
-        storeFileSizeMB += r.getStoreFileSize().get(Size.Unit.MEGABYTE);
-        memStoreSizeMB += r.getMemStoreSize().get(Size.Unit.MEGABYTE);
-        storefileIndexSizeKB += r.getStoreFileUncompressedDataIndexSize().get(Size.Unit.KILOBYTE);
+        uncompressedStoreFileSizeMB +=
+          (long) r.getUncompressedStoreFileSize().get(Size.Unit.MEGABYTE);
+        storeFileSizeMB += (long) r.getStoreFileSize().get(Size.Unit.MEGABYTE);
+        memStoreSizeMB += (long) r.getMemStoreSize().get(Size.Unit.MEGABYTE);
+        storefileIndexSizeKB +=
+          (long) r.getStoreFileUncompressedDataIndexSize().get(Size.Unit.KILOBYTE);
         readRequestsCount += r.getReadRequestCount();
         writeRequestsCount += r.getWriteRequestCount();
         filteredReadRequestsCount += r.getFilteredReadRequestCount();
-        rootLevelIndexSizeKB += r.getStoreFileRootLevelIndexSize().get(Size.Unit.KILOBYTE);
-        bloomFilterSizeMB += r.getBloomFilterSize().get(Size.Unit.MEGABYTE);
+        rootLevelIndexSizeKB += (long) r.getStoreFileRootLevelIndexSize().get(Size.Unit.KILOBYTE);
+        bloomFilterSizeMB += (long) r.getBloomFilterSize().get(Size.Unit.MEGABYTE);
         compactedCellCount += r.getCompactedCellCount();
         compactingCellCount += r.getCompactingCellCount();
       }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetrics.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetrics.java
index 05108c70e74..681b1f416c7 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetrics.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetrics.java
@@ -50,8 +50,8 @@ public interface UserMetrics {
   long getWriteRequestCount();
 
   /**
-   * @return the number of write requests and read requests and coprocessor service requests made by
-   *         the user
+   * Returns the number of write requests and read requests and coprocessor service requests made by
+   * the user
    */
   default long getRequestCount() {
     return getReadRequestCount() + getWriteRequestCount();
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetricsBuilder.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetricsBuilder.java
index ab63f19fec8..4a66283146d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetricsBuilder.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/UserMetricsBuilder.java
@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.hbase;
 
+import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
 import org.apache.hadoop.hbase.util.Strings;
@@ -30,7 +31,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.ClusterStatusProtos;
 public final class UserMetricsBuilder {
 
   public static UserMetrics toUserMetrics(ClusterStatusProtos.UserLoad userLoad) {
-    UserMetricsBuilder builder = UserMetricsBuilder.newBuilder(userLoad.getUserName().getBytes());
+    UserMetricsBuilder builder =
+      UserMetricsBuilder.newBuilder(userLoad.getUserName().getBytes(StandardCharsets.UTF_8));
     userLoad.getClientMetricsList().stream()
       .map(clientMetrics -> new ClientMetricsImpl(clientMetrics.getHostName(),
         clientMetrics.getReadRequestsCount(), clientMetrics.getWriteRequestsCount(),
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractResponse.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractResponse.java
index bb44defbac6..b0a33eda402 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractResponse.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractResponse.java
@@ -27,11 +27,9 @@ abstract class AbstractResponse {
 
   public enum ResponseType {
 
-    SINGLE(0),
-    MULTI(1);
+    SINGLE,
+    MULTI;
 
-    ResponseType(int value) {
-    }
   }
 
   public abstract ResponseType type();
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractRpcBasedConnectionRegistry.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractRpcBasedConnectionRegistry.java
index bc1febe3803..4e97dcab24d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractRpcBasedConnectionRegistry.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AbstractRpcBasedConnectionRegistry.java
@@ -135,7 +135,7 @@ abstract class AbstractRpcBasedConnectionRegistry implements ConnectionRegistry
    * Typically, you can use lambda expression to implement this interface as
    *
    * <pre>
-   * (c, s, d) -> s.xxx(c, your request here, d)
+   * (c, s, d) -&gt; s.xxx(c, your request here, d)
    * </pre>
    */
   @FunctionalInterface
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java
index 6a0913c23c7..a2f34ebbd8e 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java
@@ -116,6 +116,7 @@ public interface Admin extends Abortable, Closeable {
   Connection getConnection();
 
   /**
+   * Check if a table exists.
    * @param tableName Table to check.
    * @return <code>true</code> if table exists already.
    * @throws IOException if a remote or network exception occurs
@@ -267,8 +268,8 @@ public interface Admin extends Abortable, Closeable {
    * Get a table descriptor.
    * @param tableName as a {@link TableName}
    * @return the read-only tableDescriptor
-   * @throws org.apache.hadoop.hbase.TableNotFoundException
-   * @throws IOException                                    if a remote or network exception occurs
+   * @throws TableNotFoundException if the table was not found
+   * @throws IOException            if a remote or network exception occurs
    * @deprecated since 2.0 version and will be removed in 3.0 version. Use
    *             {@link #getDescriptor(TableName)}.
    */
@@ -280,8 +281,8 @@ public interface Admin extends Abortable, Closeable {
    * Get a table descriptor.
    * @param tableName as a {@link TableName}
    * @return the tableDescriptor
-   * @throws org.apache.hadoop.hbase.TableNotFoundException
-   * @throws IOException                                    if a remote or network exception occurs
+   * @throws TableNotFoundException if the table was not found
+   * @throws IOException            if a remote or network exception occurs
    */
   TableDescriptor getDescriptor(TableName tableName) throws TableNotFoundException, IOException;
 
@@ -290,7 +291,7 @@ public interface Admin extends Abortable, Closeable {
    * @param desc table descriptor for table
    * @throws IllegalArgumentException                          if the table name is reserved
    * @throws org.apache.hadoop.hbase.MasterNotRunningException if master is not running
-   * @throws org.apache.hadoop.hbase.TableExistsException      if table already exists (If
+   * @throws TableExistsException                              if table already exists (If
    *                                                           concurrent threads, the table may
    *                                                           have been created between
    *                                                           test-for-existence and
@@ -316,7 +317,7 @@ public interface Admin extends Abortable, Closeable {
    * @throws IOException                                       if a remote or network exception
    *                                                           occurs
    * @throws org.apache.hadoop.hbase.MasterNotRunningException if master is not running
-   * @throws org.apache.hadoop.hbase.TableExistsException      if table already exists (If
+   * @throws TableExistsException                              if table already exists (If
    *                                                           concurrent threads, the table may
    *                                                           have been created between
    *                                                           test-for-existence and
@@ -335,7 +336,7 @@ public interface Admin extends Abortable, Closeable {
    *                                                           split keys are repeated and if the
    *                                                           split key has empty byte array.
    * @throws org.apache.hadoop.hbase.MasterNotRunningException if master is not running
-   * @throws org.apache.hadoop.hbase.TableExistsException      if table already exists (If
+   * @throws TableExistsException                              if table already exists (If
    *                                                           concurrent threads, the table may
    *                                                           have been created between
    *                                                           test-for-existence and
@@ -574,6 +575,7 @@ public interface Admin extends Abortable, Closeable {
   HTableDescriptor[] disableTables(Pattern pattern) throws IOException;
 
   /**
+   * Check if a table is enabled.
    * @param tableName name of table to check
    * @return <code>true</code> if table is on-line
    * @throws IOException if a remote or network exception occurs
@@ -581,6 +583,7 @@ public interface Admin extends Abortable, Closeable {
   boolean isTableEnabled(TableName tableName) throws IOException;
 
   /**
+   * Check if a table is disabled.
    * @param tableName name of table to check
    * @return <code>true</code> if table is off-line
    * @throws IOException if a remote or network exception occurs
@@ -588,6 +591,7 @@ public interface Admin extends Abortable, Closeable {
   boolean isTableDisabled(TableName tableName) throws IOException;
 
   /**
+   * Check if a table is available.
    * @param tableName name of table to check
    * @return <code>true</code> if all regions of the table are available
    * @throws IOException if a remote or network exception occurs
@@ -1646,6 +1650,7 @@ public interface Admin extends Abortable, Closeable {
   ClusterMetrics getClusterMetrics(EnumSet<Option> options) throws IOException;
 
   /**
+   * Get the current active master.
    * @return current master server name
    * @throws IOException if a remote or network exception occurs
    */
@@ -1654,6 +1659,7 @@ public interface Admin extends Abortable, Closeable {
   }
 
   /**
+   * Get a list of current backup masters.
    * @return current backup master list
    * @throws IOException if a remote or network exception occurs
    */
@@ -1662,6 +1668,7 @@ public interface Admin extends Abortable, Closeable {
   }
 
   /**
+   * Get the live server list.
    * @return current live region servers list
    * @throws IOException if a remote or network exception occurs
    */
@@ -1772,7 +1779,7 @@ public interface Admin extends Abortable, Closeable {
    * Get a namespace descriptor by name.
    * @param name name of namespace descriptor
    * @return A descriptor
-   * @throws org.apache.hadoop.hbase.NamespaceNotFoundException
+   * @throws org.apache.hadoop.hbase.NamespaceNotFoundException if the namespace was not found
    * @throws IOException                                        if a remote or network exception
    *                                                            occurs
    */
@@ -1929,9 +1936,8 @@ public interface Admin extends Abortable, Closeable {
    * this method returns. As a side effect of this call, the named region server may schedule store
    * flushes at the request of the wal.
    * @param serverName The servername of the regionserver.
-   * @throws IOException                                                      if a remote or network
-   *                                                                          exception occurs
-   * @throws org.apache.hadoop.hbase.regionserver.wal.FailedLogCloseException
+   * @throws IOException             if a remote or network exception occurs
+   * @throws FailedLogCloseException if we failed to close the WAL
    */
   void rollWALWriter(ServerName serverName) throws IOException, FailedLogCloseException;
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Append.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Append.java
index bf1a29196db..31a57eacf4d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Append.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Append.java
@@ -47,7 +47,7 @@ import org.slf4j.LoggerFactory;
 @InterfaceAudience.Public
 public class Append extends Mutation {
   private static final Logger LOG = LoggerFactory.getLogger(Append.class);
-  private static final long HEAP_OVERHEAD = ClassSize.REFERENCE + ClassSize.TIMERANGE;
+  private static final long HEAP_OVERHEAD = (long) ClassSize.REFERENCE + ClassSize.TIMERANGE;
   private TimeRange tr = TimeRange.allTime();
 
   /**
@@ -166,6 +166,7 @@ public class Append extends Mutation {
    * Add column and value to this Append operation. n * @return This instance
    */
   @SuppressWarnings("unchecked")
+  @Override
   public Append add(final Cell cell) {
     try {
       super.add(cell);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdmin.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdmin.java
index 2d6d499042e..ca08c9dfc10 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdmin.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdmin.java
@@ -61,6 +61,7 @@ import org.apache.hbase.thirdparty.com.google.common.collect.ImmutableList;
 public interface AsyncAdmin {
 
   /**
+   * Check if a table exists.
    * @param tableName Table to check.
    * @return True if table exists already. The return value will be wrapped by a
    *         {@link CompletableFuture}.
@@ -210,6 +211,7 @@ public interface AsyncAdmin {
   CompletableFuture<Void> disableTable(TableName tableName);
 
   /**
+   * Check if a table is enabled.
    * @param tableName name of table to check
    * @return true if table is on-line. The return value will be wrapped by a
    *         {@link CompletableFuture}.
@@ -217,6 +219,7 @@ public interface AsyncAdmin {
   CompletableFuture<Boolean> isTableEnabled(TableName tableName);
 
   /**
+   * Check if a table is disabled.
    * @param tableName name of table to check
    * @return true if table is off-line. The return value will be wrapped by a
    *         {@link CompletableFuture}.
@@ -224,6 +227,7 @@ public interface AsyncAdmin {
   CompletableFuture<Boolean> isTableDisabled(TableName tableName);
 
   /**
+   * Check if a table is available.
    * @param tableName name of table to check
    * @return true if all regions of the table are available. The return value will be wrapped by a
    *         {@link CompletableFuture}.
@@ -598,11 +602,15 @@ public interface AsyncAdmin {
   CompletableFuture<Void> splitRegion(byte[] regionName, byte[] splitPoint);
 
   /**
+   * Assign an individual region.
    * @param regionName Encoded or full name of region to assign.
    */
   CompletableFuture<Void> assign(byte[] regionName);
 
   /**
+   * Unassign a region from current hosting regionserver. Region will then be assigned to a
+   * regionserver chosen at random. Region could be reassigned back to the same server. Use
+   * {@link #move(byte[], ServerName)} if you want to control the region movement.
    * @param regionName Encoded or full name of region to unassign.
    */
   CompletableFuture<Void> unassign(byte[] regionName);
@@ -1154,19 +1162,21 @@ public interface AsyncAdmin {
   CompletableFuture<Void> rollWALWriter(ServerName serverName);
 
   /**
-   * Clear compacting queues on a region server. n * @param queues the set of queue name
+   * Clear compacting queues on a region server.
+   * @param serverName The servername of the region server.
+   * @param queues     the set of queue name
    */
   CompletableFuture<Void> clearCompactionQueues(ServerName serverName, Set<String> queues);
 
   /**
-   * Get a list of {@link RegionMetrics} of all regions hosted on a region seerver. n * @return a
-   * list of {@link RegionMetrics} wrapped by {@link CompletableFuture}
+   * Get a list of {@link RegionMetrics} of all regions hosted on a region server.
+   * @return list of {@link RegionMetrics} wrapped by {@link CompletableFuture}
    */
   CompletableFuture<List<RegionMetrics>> getRegionMetrics(ServerName serverName);
 
   /**
-   * Get a list of {@link RegionMetrics} of all regions hosted on a region seerver for a table. nn
-   * * @return a list of {@link RegionMetrics} wrapped by {@link CompletableFuture}
+   * Get a list of {@link RegionMetrics} of all regions hosted on a region server for a table.
+   * @return a list of {@link RegionMetrics} wrapped by {@link CompletableFuture}
    */
   CompletableFuture<List<RegionMetrics>> getRegionMetrics(ServerName serverName,
     TableName tableName);
@@ -1227,8 +1237,8 @@ public interface AsyncAdmin {
   CompletableFuture<Optional<Long>> getLastMajorCompactionTimestampForRegion(byte[] regionName);
 
   /**
-   * @return the list of supported security capabilities. The return value will be wrapped by a
-   *         {@link CompletableFuture}.
+   * Returns the list of supported security capabilities. The return value will be wrapped by a
+   * {@link CompletableFuture}.
    */
   CompletableFuture<List<SecurityCapability>> getSecurityCapabilities();
 
@@ -1372,9 +1382,7 @@ public interface AsyncAdmin {
    * one line lambda expression, like:
    *
    * <pre>
-   * <code>
-   * channel -> xxxService.newStub(channel)
-   * </code>
+   * channel -&gt; xxxService.newStub(channel)
    * </pre>
    *
    * @param stubMaker a delegation to the actual {@code newStub} call.
@@ -1395,9 +1403,7 @@ public interface AsyncAdmin {
    * one line lambda expression, like:
    *
    * <pre>
-   * <code>
-   * channel -> xxxService.newStub(channel)
-   * </code>
+   * channel -&gt; xxxService.newStub(channel)
    * </pre>
    *
    * @param stubMaker  a delegation to the actual {@code newStub} call.
@@ -1613,7 +1619,6 @@ public interface AsyncAdmin {
    * @param serverType   enum for server type: HMaster or RegionServer
    * @param limit        put a limit to list of records that server should send in response
    * @param filterParams additional filter params
-   * @return Log entries representing online records from servers
    */
   CompletableFuture<List<LogEntry>> getLogEntries(Set<ServerName> serverNames, String logType,
     ServerType serverType, int limit, Map<String, Object> filterParams);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdminRequestRetryingCaller.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdminRequestRetryingCaller.java
index de6e967f21c..d3bec8b3cfb 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdminRequestRetryingCaller.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncAdminRequestRetryingCaller.java
@@ -29,9 +29,6 @@ import org.apache.hbase.thirdparty.io.netty.util.Timer;
 
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.AdminService;
 
-/**
- * @since 2.0.0
- */
 @InterfaceAudience.Private
 public class AsyncAdminRequestRetryingCaller<T> extends AsyncRpcRetryingCaller<T> {
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncRequestFutureImpl.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncRequestFutureImpl.java
index cfcb8daf488..987d86bd8aa 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncRequestFutureImpl.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncRequestFutureImpl.java
@@ -539,7 +539,7 @@ class AsyncRequestFutureImpl<CResult> implements AsyncRequestFuture {
           runnable.run();
         } else {
           try {
-            pool.submit(runnable);
+            pool.execute(runnable);
           } catch (Throwable t) {
             if (t instanceof RejectedExecutionException) {
               // This should never happen. But as the pool is provided by the end user,
@@ -564,6 +564,7 @@ class AsyncRequestFutureImpl<CResult> implements AsyncRequestFuture {
     }
   }
 
+  @SuppressWarnings("MixedMutabilityReturnType")
   private Collection<? extends Runnable> getNewMultiActionRunnable(ServerName server,
     MultiAction multiAction, int numAttempt) {
     // no stats to manage, just do the standard action
@@ -644,7 +645,7 @@ class AsyncRequestFutureImpl<CResult> implements AsyncRequestFuture {
       // Start the thread that may kick off replica gets.
       // TODO: we could do it on the same thread, but it's a user thread, might be a bad idea.
       try {
-        pool.submit(replicaRunnable);
+        pool.execute(replicaRunnable);
       } catch (RejectedExecutionException ree) {
         LOG.warn("id=" + asyncProcess.id + " replica task rejected by pool; no replica calls", ree);
       }
@@ -770,6 +771,7 @@ class AsyncRequestFutureImpl<CResult> implements AsyncRequestFuture {
   private void logNoResubmit(ServerName oldServer, int numAttempt, int failureCount,
     Throwable throwable, int failed, int stopped) {
     if (failureCount != 0 || numAttempt > asyncProcess.startLogErrorsCnt + 1) {
+      @SuppressWarnings("JavaUtilDate")
       String timeStr = new Date(errorsByServer.getStartTrackingTime()).toString();
       String logMessage = createLog(numAttempt, failureCount, 0, oldServer, throwable, -1, false,
         timeStr, failed, stopped);
@@ -955,14 +957,14 @@ class AsyncRequestFutureImpl<CResult> implements AsyncRequestFuture {
     if (result == null) {
       throw new RuntimeException("Result cannot be null");
     }
-    ReplicaResultState state = null;
     boolean isStale = !RegionReplicaUtil.isDefaultReplica(action.getReplicaId());
     int index = action.getOriginalIndex();
     if (results == null) {
       decActionCounter(index);
       return; // Simple case, no replica requests.
     }
-    state = trySetResultSimple(index, action.getAction(), false, result, null, isStale);
+    ReplicaResultState state =
+      trySetResultSimple(index, action.getAction(), false, result, null, isStale);
     if (state == null) {
       return; // Simple case, no replica requests.
     }
@@ -995,7 +997,6 @@ class AsyncRequestFutureImpl<CResult> implements AsyncRequestFuture {
    * @param server    The source server.
    */
   private void setError(int index, Row row, Throwable throwable, ServerName server) {
-    ReplicaResultState state = null;
     if (results == null) {
       // Note that we currently cannot have replica requests with null results. So it shouldn't
       // happen that multiple replica calls will call dAC for same actions with results == null.
@@ -1004,7 +1005,7 @@ class AsyncRequestFutureImpl<CResult> implements AsyncRequestFuture {
       decActionCounter(index);
       return; // Simple case, no replica requests.
     }
-    state = trySetResultSimple(index, row, true, throwable, server, false);
+    ReplicaResultState state = trySetResultSimple(index, row, true, throwable, server, false);
     if (state == null) {
       return; // Simple case, no replica requests.
     }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTable.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTable.java
index aa696966ca6..2bd6b50df22 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTable.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTable.java
@@ -223,16 +223,14 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
    * This is a fluent style API, the code is like:
    *
    * <pre>
-   * <code>
    * table.checkAndMutate(row, family).qualifier(qualifier).ifNotExists().thenPut(put)
-   *     .thenAccept(succ -> {
-   *       if (succ) {
-   *         System.out.println("Check and put succeeded");
-   *       } else {
-   *         System.out.println("Check and put failed");
-   *       }
-   *     });
-   * </code>
+   *   .thenAccept(succ -&gt; {
+   *     if (succ) {
+   *       System.out.println("Check and put succeeded");
+   *     } else {
+   *       System.out.println("Check and put failed");
+   *     }
+   *   });
    * </pre>
    *
    * @deprecated Since 2.4.0, will be removed in 4.0.0. For internal test use only, do not use it
@@ -250,11 +248,13 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
   interface CheckAndMutateBuilder {
 
     /**
+     * Match a qualifier.
      * @param qualifier column qualifier to check.
      */
     CheckAndMutateBuilder qualifier(byte[] qualifier);
 
     /**
+     * Match a timerange.
      * @param timeRange time range to check.
      */
     CheckAndMutateBuilder timeRange(TimeRange timeRange);
@@ -273,12 +273,14 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
     }
 
     /**
+     * Compare a value
      * @param compareOp comparison operator to use
      * @param value     the expected value
      */
     CheckAndMutateBuilder ifMatches(CompareOperator compareOp, byte[] value);
 
     /**
+     * Specify a Put to commit if the check succeeds.
      * @param put data to put if check succeeds
      * @return {@code true} if the new put was executed, {@code false} otherwise. The return value
      *         will be wrapped by a {@link CompletableFuture}.
@@ -286,6 +288,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
     CompletableFuture<Boolean> thenPut(Put put);
 
     /**
+     * Specify a Delete to commit if the check succeeds.
      * @param delete data to delete if check succeeds
      * @return {@code true} if the new delete was executed, {@code false} otherwise. The return
      *         value will be wrapped by a {@link CompletableFuture}.
@@ -293,6 +296,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
     CompletableFuture<Boolean> thenDelete(Delete delete);
 
     /**
+     * Specify a RowMutations to commit if the check succeeds.
      * @param mutation mutations to perform if check succeeds
      * @return true if the new mutation was executed, false otherwise. The return value will be
      *         wrapped by a {@link CompletableFuture}.
@@ -308,16 +312,13 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
    * execute it. This is a fluent style API, the code is like:
    *
    * <pre>
-   * <code>
-   * table.checkAndMutate(row, filter).thenPut(put)
-   *     .thenAccept(succ -> {
-   *       if (succ) {
-   *         System.out.println("Check and put succeeded");
-   *       } else {
-   *         System.out.println("Check and put failed");
-   *       }
-   *     });
-   * </code>
+   * table.checkAndMutate(row, filter).thenPut(put).thenAccept(succ -&gt; {
+   *   if (succ) {
+   *     System.out.println("Check and put succeeded");
+   *   } else {
+   *     System.out.println("Check and put failed");
+   *   }
+   * });
    * </pre>
    *
    * @deprecated Since 2.4.0, will be removed in 4.0.0. For internal test use only, do not use it
@@ -335,11 +336,13 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
   interface CheckAndMutateWithFilterBuilder {
 
     /**
+     * Match a timerange.
      * @param timeRange time range to check.
      */
     CheckAndMutateWithFilterBuilder timeRange(TimeRange timeRange);
 
     /**
+     * Specify a Put to commit if the check succeeds.
      * @param put data to put if check succeeds
      * @return {@code true} if the new put was executed, {@code false} otherwise. The return value
      *         will be wrapped by a {@link CompletableFuture}.
@@ -347,6 +350,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
     CompletableFuture<Boolean> thenPut(Put put);
 
     /**
+     * Specify a Delete to commit if the check succeeds.
      * @param delete data to delete if check succeeds
      * @return {@code true} if the new delete was executed, {@code false} otherwise. The return
      *         value will be wrapped by a {@link CompletableFuture}.
@@ -354,6 +358,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
     CompletableFuture<Boolean> thenDelete(Delete delete);
 
     /**
+     * Specify a RowMutations to commit if the check succeeds.
      * @param mutation mutations to perform if check succeeds
      * @return true if the new mutation was executed, false otherwise. The return value will be
      *         wrapped by a {@link CompletableFuture}.
@@ -440,16 +445,14 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
    * <p>
    *
    * <pre>
-   * <code>
-   * table.scanAll(new Scan().withStartRow(row, false).setLimit(1)).thenAccept(results -> {
+   * table.scanAll(new Scan().withStartRow(row, false).setLimit(1)).thenAccept(results -&gt; {
    *   if (results.isEmpty()) {
-   *      System.out.println("No row after " + Bytes.toStringBinary(row));
+   *     System.out.println("No row after " + Bytes.toStringBinary(row));
    *   } else {
    *     System.out.println("The closest row after " + Bytes.toStringBinary(row) + " is "
-   *         + Bytes.toStringBinary(results.stream().findFirst().get().getRow()));
+   *       + Bytes.toStringBinary(results.stream().findFirst().get().getRow()));
    *   }
    * });
-   * </code>
    * </pre>
    * <p>
    * If your result set is very large, you should use other scan method to get a scanner or use
@@ -574,9 +577,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
    * one line lambda expression, like:
    *
    * <pre>
-   * <code>
-   * channel -> xxxService.newStub(channel)
-   * </code>
+   * channel -&gt; xxxService.newStub(channel)
    * </pre>
    *
    * @param stubMaker a delegation to the actual {@code newStub} call.
@@ -609,7 +610,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
    *
    * <pre>
    * locateThenCall(byte[] row) {
-   *   locate(row).whenComplete((location, locateError) -> {
+   *   locate(row).whenComplete((location, locateError) -&gt; {
    *     if (locateError != null) {
    *       callback.onError(locateError);
    *       return;
@@ -621,7 +622,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
    *     } else {
    *       locateThenCall(region.getEndKey());
    *     }
-   *     sendCall().whenComplete((resp, error) -> {
+   *     sendCall().whenComplete((resp, error) -&gt; {
    *       if (error != null) {
    *         callback.onRegionError(region, error);
    *       } else {
@@ -639,12 +640,14 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
   interface CoprocessorCallback<R> {
 
     /**
+     * Indicate that the respose of a region is available
      * @param region the region that the response belongs to
      * @param resp   the response of the coprocessor call
      */
     void onRegionComplete(RegionInfo region, R resp);
 
     /**
+     * Indicate that the error for a region is available
      * @param region the region that the error belongs to
      * @param error  the response error of the coprocessor call
      */
@@ -675,6 +678,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
   interface CoprocessorServiceBuilder<S, R> {
 
     /**
+     * Specify a start row
      * @param startKey start region selection with region containing this row, inclusive.
      */
     default CoprocessorServiceBuilder<S, R> fromRow(byte[] startKey) {
@@ -682,12 +686,14 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
     }
 
     /**
+     * Specify a start row
      * @param startKey  start region selection with region containing this row
      * @param inclusive whether to include the startKey
      */
     CoprocessorServiceBuilder<S, R> fromRow(byte[] startKey, boolean inclusive);
 
     /**
+     * Specify a stop row
      * @param endKey select regions up to and including the region containing this row, exclusive.
      */
     default CoprocessorServiceBuilder<S, R> toRow(byte[] endKey) {
@@ -695,6 +701,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
     }
 
     /**
+     * Specify a stop row
      * @param endKey    select regions up to and including the region containing this row
      * @param inclusive whether to include the endKey
      */
@@ -716,9 +723,7 @@ public interface AsyncTable<C extends ScanResultConsumerBase> {
    * is only a one line lambda expression, like:
    *
    * <pre>
-   * <code>
-   * channel -> xxxService.newStub(channel)
-   * </code>
+   * channel -&gt; xxxService.newStub(channel)
    * </pre>
    *
    * @param stubMaker a delegation to the actual {@code newStub} call.
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTableRegionLocator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTableRegionLocator.java
index 11867ca333b..9fa32ee64aa 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTableRegionLocator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTableRegionLocator.java
@@ -89,7 +89,6 @@ public interface AsyncTableRegionLocator {
    * Find all the replicas for the region on which the given row is being served.
    * @param row Row to find.
    * @return Locations for all the replicas of the row.
-   * @throws IOException if a remote or network exception occurs
    */
   default CompletableFuture<List<HRegionLocation>> getRegionLocations(byte[] row) {
     return getRegionLocations(row, false);
@@ -100,7 +99,6 @@ public interface AsyncTableRegionLocator {
    * @param row    Row to find.
    * @param reload true to reload information or false to use cached information
    * @return Locations for all the replicas of the row.
-   * @throws IOException if a remote or network exception occurs
    */
   CompletableFuture<List<HRegionLocation>> getRegionLocations(byte[] row, boolean reload);
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/BufferedMutatorParams.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/BufferedMutatorParams.java
index da3aa7f0975..ee614716f86 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/BufferedMutatorParams.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/BufferedMutatorParams.java
@@ -147,8 +147,8 @@ public class BufferedMutatorParams implements Cloneable {
   }
 
   /**
-   * @return Name of the class we will use when we construct a {@link BufferedMutator} instance or
-   *         null if default implementation.
+   * Returns Name of the class we will use when we construct a {@link BufferedMutator} instance or
+   * null if default implementation.
    */
   public String getImplementationClassName() {
     return this.implementationClassName;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
index 1a148153bba..67549f9d610 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CatalogReplicaLoadBalanceSimpleSelector.java
@@ -129,6 +129,7 @@ class CatalogReplicaLoadBalanceSimpleSelector
    * Selector's internal state.
    * @param loc the location which causes exception.
    */
+  @Override
   public void onError(HRegionLocation loc) {
     ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache = computeIfAbsent(staleCache,
       loc.getRegion().getTable(), () -> new ConcurrentSkipListMap<>(BYTES_COMPARATOR));
@@ -160,18 +161,19 @@ class CatalogReplicaLoadBalanceSimpleSelector
    * When it looks up a location, it will call this method to find a replica region to go. For a
    * normal case, > 99% of region locations from catalog/meta replica will be up to date. In extreme
    * cases such as region server crashes, it will depends on how fast replication catches up.
-   * @param tablename  table name it looks up
+   * @param tableName  table name it looks up
    * @param row        key it looks up.
    * @param locateType locateType, Only BEFORE and CURRENT will be passed in.
    * @return catalog replica id
    */
-  public int select(final TableName tablename, final byte[] row,
+  @Override
+  public int select(final TableName tableName, final byte[] row,
     final RegionLocateType locateType) {
     Preconditions.checkArgument(
       locateType == RegionLocateType.BEFORE || locateType == RegionLocateType.CURRENT,
       "Expected type BEFORE or CURRENT but got: %s", locateType);
 
-    ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache = staleCache.get(tablename);
+    ConcurrentNavigableMap<byte[], StaleLocationCacheEntry> tableCache = staleCache.get(tableName);
 
     // If there is no entry in StaleCache, select a random replica id.
     if (tableCache == null) {
@@ -200,7 +202,7 @@ class CatalogReplicaLoadBalanceSimpleSelector
       (EnvironmentEdgeManager.currentTime() - entry.getValue().getTimestamp())
           >= STALE_CACHE_TIMEOUT_IN_MILLISECONDS
     ) {
-      LOG.debug("Entry for table {} with startKey {}, {} times out", tablename, entry.getKey(),
+      LOG.debug("Entry for table {} with startKey {}, {} times out", tableName, entry.getKey(),
         entry);
       tableCache.remove(entry.getKey());
       return getRandomReplicaId();
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CheckAndMutate.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CheckAndMutate.java
index e8949ee65ec..7f8d0677b6b 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CheckAndMutate.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CheckAndMutate.java
@@ -97,6 +97,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Check for match
      * @param family    family to check
      * @param qualifier qualifier to check
      * @param compareOp comparison operator to use
@@ -113,6 +114,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Check for match
      * @param filter filter to check
      * @return the CheckAndMutate object
      */
@@ -122,6 +124,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Specify a timerange
      * @param timeRange time range to check
      * @return the CheckAndMutate object
      */
@@ -144,6 +147,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Build the CheckAndMutate object
      * @param put data to put if check succeeds
      * @return a CheckAndMutate object
      */
@@ -157,6 +161,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Build the CheckAndMutate object
      * @param delete data to delete if check succeeds
      * @return a CheckAndMutate object
      */
@@ -170,6 +175,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Build the CheckAndMutate object with an Increment to commit if the check succeeds.
      * @param increment data to increment if check succeeds
      * @return a CheckAndMutate object
      */
@@ -183,6 +189,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Build the CheckAndMutate object with an Append to commit if the check succeeds.
      * @param append data to append if check succeeds
      * @return a CheckAndMutate object
      */
@@ -196,6 +203,7 @@ public final class CheckAndMutate implements Row {
     }
 
     /**
+     * Build the CheckAndMutate object with a RowMutations to commit if the check succeeds.
      * @param mutations mutations to perform if check succeeds
      * @return a CheckAndMutate object
      */
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientAsyncPrefetchScanner.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientAsyncPrefetchScanner.java
index 6c221590500..77ec41ec4e9 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientAsyncPrefetchScanner.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientAsyncPrefetchScanner.java
@@ -94,34 +94,35 @@ public class ClientAsyncPrefetchScanner extends ClientSimpleScanner {
   public Result next() throws IOException {
     try (Scope ignored = span.makeCurrent()) {
       lock.lock();
-      while (cache.isEmpty()) {
+      try {
+        while (cache.isEmpty()) {
+          handleException();
+          if (this.closed) {
+            return null;
+          }
+          try {
+            notEmpty.await();
+          } catch (InterruptedException e) {
+            span.recordException(e);
+            throw new InterruptedIOException("Interrupted when wait to load cache");
+          }
+        }
+        Result result = pollCache();
+        if (prefetchCondition()) {
+          notFull.signalAll();
+        }
+        return result;
+      } finally {
+        lock.unlock();
         handleException();
-        if (this.closed) {
-          return null;
-        }
-        try {
-          notEmpty.await();
-        } catch (InterruptedException e) {
-          span.recordException(e);
-          throw new InterruptedIOException("Interrupted when wait to load cache");
-        }
       }
-
-      Result result = pollCache();
-      if (prefetchCondition()) {
-        notFull.signalAll();
-      }
-      return result;
-    } finally {
-      lock.unlock();
-      handleException();
     }
   }
 
   @Override
   public void close() {
+    lock.lock();
     try {
-      lock.lock();
       super.close();
       closed = true;
       notFull.signalAll();
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientIdGenerator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientIdGenerator.java
index f5bedbe88d2..ee497ef56c5 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientIdGenerator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientIdGenerator.java
@@ -19,6 +19,7 @@ package org.apache.hadoop.hbase.client;
 
 import java.io.IOException;
 import java.lang.management.ManagementFactory;
+import java.util.List;
 import org.apache.hadoop.hbase.util.Addressing;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
@@ -26,6 +27,9 @@ import org.apache.yetus.audience.InterfaceAudience;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import org.apache.hbase.thirdparty.com.google.common.base.Splitter;
+import org.apache.hbase.thirdparty.com.google.common.collect.Iterators;
+
 /**
  * The class that is able to determine some unique strings for the client, such as an IP address,
  * PID, and composite deterministic ID.
@@ -38,8 +42,8 @@ final class ClientIdGenerator {
   }
 
   /**
-   * @return a unique ID incorporating IP address, PID, TID and timer. Might be an overkill... Note
-   *         though that new UUID in java by default is just a random number.
+   * Returns a unique ID incorporating IP address, PID, TID and timer. Might be an overkill... Note
+   * though that new UUID in java by default is just a random number.
    */
   public static byte[] generateClientId() {
     byte[] selfBytes = getIpAddressBytes();
@@ -61,10 +65,10 @@ final class ClientIdGenerator {
   /** Returns PID of the current process, if it can be extracted from JVM name, or null. */
   public static Long getPid() {
     String name = ManagementFactory.getRuntimeMXBean().getName();
-    String[] nameParts = name.split("@");
-    if (nameParts.length == 2) { // 12345@somewhere
+    List<String> nameParts = Splitter.on('@').splitToList(name);
+    if (nameParts.size() == 2) { // 12345@somewhere
       try {
-        return Long.parseLong(nameParts[0]);
+        return Long.parseLong(Iterators.get(nameParts.iterator(), 0));
       } catch (NumberFormatException ex) {
         LOG.warn("Failed to get PID from [" + name + "]", ex);
       }
@@ -75,8 +79,8 @@ final class ClientIdGenerator {
   }
 
   /**
-   * @return Some IPv4/IPv6 address available on the current machine that is up, not virtual and not
-   *         a loopback address. Empty array if none can be found or error occurred.
+   * Returns Some IPv4/IPv6 address available on the current machine that is up, not virtual and not
+   * a loopback address. Empty array if none can be found or error occurred.
    */
   public static byte[] getIpAddressBytes() {
     try {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java
index 1d656873bbe..f240798c58d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java
@@ -327,7 +327,7 @@ public abstract class ClientScanner extends AbstractClientScanner {
     return cache != null ? cache.size() : 0;
   }
 
-  private boolean scanExhausted(Result[] values) {
+  private boolean scanExhausted() {
     return callable.moreResultsForScan() == MoreResults.NO;
   }
 
@@ -484,7 +484,7 @@ public abstract class ClientScanner extends AbstractClientScanner {
         assert newLimit >= 0;
         scan.setLimit(newLimit);
       }
-      if (scan.getLimit() == 0 || scanExhausted(values)) {
+      if (scan.getLimit() == 0 || scanExhausted()) {
         closeScanner();
         closed = true;
         break;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientServiceCallable.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientServiceCallable.java
index 367ad3bda48..c9220540e45 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientServiceCallable.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientServiceCallable.java
@@ -29,7 +29,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos;
 /**
  * A RegionServerCallable set to use the Client protocol. Also includes some utility methods so can
  * hide protobuf references here rather than have them sprinkled about the code base.
- * @param <T>
  */
 @InterfaceAudience.Private
 public abstract class ClientServiceCallable<T>
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClusterConnection.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClusterConnection.java
index 849745b89eb..219e63a6ffc 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClusterConnection.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClusterConnection.java
@@ -72,6 +72,7 @@ public interface ClusterConnection extends Connection {
   boolean isTableEnabled(TableName tableName) throws IOException;
 
   /**
+   * Check if a table is disabled.
    * @param tableName table name
    * @return true if the table is disabled, false otherwise
    * @throws IOException if a remote or network exception occurs
@@ -95,6 +96,7 @@ public interface ClusterConnection extends Connection {
   HRegionLocation locateRegion(final TableName tableName, final byte[] row) throws IOException;
 
   /**
+   * Clear the region location cache.
    * @deprecated {@link #clearRegionLocationCache()} instead.
    */
   @Deprecated
@@ -179,6 +181,7 @@ public interface ClusterConnection extends Connection {
     final boolean offlined) throws IOException;
 
   /**
+   * Gets the locations of the region in the specified table, <i>tableName</i>, for a given row.
    * @param tableName table to get regions of
    * @param row       the row
    * @param useCache  Should we use the cache to retrieve the region information.
@@ -190,6 +193,7 @@ public interface ClusterConnection extends Connection {
     throws IOException;
 
   /**
+   * Gets the locations of the region in the specified table, <i>tableName</i>, for a given row.
    * @param tableName table to get regions of
    * @param row       the row
    * @param useCache  Should we use the cache to retrieve the region information.
@@ -280,8 +284,8 @@ public interface ClusterConnection extends Connection {
   MetricsConnection getConnectionMetrics();
 
   /**
-   * @return true when this connection uses a {@link org.apache.hadoop.hbase.codec.Codec} and so
-   *         supports cell blocks.
+   * Returns true when this connection uses a {@link org.apache.hadoop.hbase.codec.Codec} and so
+   * supports cell blocks.
    */
   boolean hasCellBlockSupport();
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptor.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptor.java
index b3d8e4fd600..d73e67ee0fb 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptor.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptor.java
@@ -98,10 +98,7 @@ public interface ColumnFamilyDescriptor {
   /** Returns an unmodifiable map. */
   Map<String, String> getConfiguration();
 
-  /**
-   * @param key the key whose associated value is to be returned
-   * @return accessing the configuration value by key.
-   */
+  /** Returns accessing the configuration value by key. */
   String getConfigurationValue(String key);
 
   /** Returns replication factor set for this CF */
@@ -117,8 +114,8 @@ public interface ColumnFamilyDescriptor {
   String getEncryptionType();
 
   /**
-   * @return in-memory compaction policy if set for the cf. Returns null if no policy is set for for
-   *         this column family
+   * Returns in-memory compaction policy if set for the cf. Returns null if no policy is set for for
+   * this column family
    */
   MemoryCompactionPolicy getInMemoryCompaction();
 
@@ -163,32 +160,35 @@ public interface ColumnFamilyDescriptor {
   int getTimeToLive();
 
   /**
+   * Get a configuration value.
    * @param key The key.
    * @return A clone value. Null if no mapping for the key
    */
   Bytes getValue(Bytes key);
 
   /**
+   * Get a configuration value.
    * @param key The key.
    * @return A clone value. Null if no mapping for the key
    */
   String getValue(String key);
 
   /**
+   * Get a configuration value.
    * @param key The key.
    * @return A clone value. Null if no mapping for the key
    */
   byte[] getValue(byte[] key);
 
   /**
-   * It clone all bytes of all elements.
+   * Get all configuration values. It clone all bytes of all elements.
    * @return All values
    */
   Map<Bytes, Bytes> getValues();
 
   /**
-   * @return True if hfile DATA type blocks should be cached (You cannot disable caching of INDEX
-   *         and BLOOM type blocks).
+   * Returns True if hfile DATA type blocks should be cached (You cannot disable caching of INDEX
+   * and BLOOM type blocks).
    */
   boolean isBlockCacheEnabled();
 
@@ -202,8 +202,8 @@ public interface ColumnFamilyDescriptor {
   boolean isCacheIndexesOnWrite();
 
   /**
-   * @return Whether KV tags should be compressed along with DataBlockEncoding. When no
-   *         DataBlockEncoding is been used, this is having no effect.
+   * Returns Whether KV tags should be compressed along with DataBlockEncoding. When no
+   * DataBlockEncoding is been used, this is having no effect.
    */
   boolean isCompressTags();
 
@@ -211,8 +211,8 @@ public interface ColumnFamilyDescriptor {
   boolean isEvictBlocksOnClose();
 
   /**
-   * @return True if we are to favor keeping all values for this column family in the HRegionServer
-   *         cache.
+   * Returns True if we are to favor keeping all values for this column family in the HRegionServer
+   * cache.
    */
   boolean isInMemory();
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptorBuilder.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptorBuilder.java
index 37a63c955b2..814994abd39 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptorBuilder.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ColumnFamilyDescriptorBuilder.java
@@ -42,9 +42,6 @@ import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos.ColumnFamilySchema;
 
-/**
- * @since 2.0.0
- */
 @InterfaceAudience.Public
 public class ColumnFamilyDescriptorBuilder {
   // For future backward compatibility
@@ -330,6 +327,7 @@ public class ColumnFamilyDescriptorBuilder {
   }
 
   /**
+   * Check if the column family name is legal.
    * @param b Family name.
    * @return <code>b</code>
    * @throws IllegalArgumentException If not null and not a legitimate family name: i.e. 'printable'
@@ -398,6 +396,7 @@ public class ColumnFamilyDescriptorBuilder {
   }
 
   /**
+   * Serialize the table descriptor to a byte array.
    * @param desc The table descriptor to serialize
    * @return This instance serialized with pb with pb magic prefix
    */
@@ -691,11 +690,6 @@ public class ColumnFamilyDescriptorBuilder {
       return Collections.unmodifiableMap(values);
     }
 
-    /**
-     * @param key   The key.
-     * @param value The value.
-     * @return this (for chained invocation)
-     */
     public ModifyableColumnFamilyDescriptor setValue(byte[] key, byte[] value) {
       return setValue(toBytesOrNull(key, Function.identity()),
         toBytesOrNull(value, Function.identity()));
@@ -709,11 +703,6 @@ public class ColumnFamilyDescriptorBuilder {
       return setValue(key, toBytesOrNull(value, Bytes::toBytes));
     }
 
-    /**
-     * @param key   The key.
-     * @param value The value.
-     * @return this (for chained invocation)
-     */
     private ModifyableColumnFamilyDescriptor setValue(Bytes key, Bytes value) {
       if (value == null || value.getLength() == 0) {
         values.remove(key);
@@ -723,10 +712,6 @@ public class ColumnFamilyDescriptorBuilder {
       return this;
     }
 
-    /**
-     * @param key Key whose key and value we're to remove from HCD parameters.
-     * @return this (for chained invocation)
-     */
     public ModifyableColumnFamilyDescriptor removeValue(final Bytes key) {
       return setValue(key, (Bytes) null);
     }
@@ -758,6 +743,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the maximum number of versions to retain.
      * @param maxVersions maximum number of versions
      * @return this (for chained invocation)
      */
@@ -777,7 +763,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
-     * Set minimum and maximum versions to keep
+     * Set minimum and maximum versions to keep.
      * @param minVersions minimal number of versions
      * @param maxVersions maximum number of versions
      * @return this (for chained invocation)
@@ -804,10 +790,6 @@ public class ColumnFamilyDescriptorBuilder {
       return getStringOrDefault(BLOCKSIZE_BYTES, Integer::valueOf, DEFAULT_BLOCKSIZE);
     }
 
-    /**
-     * @param s Blocksize to use when writing out storefiles/hfiles on this column family.
-     * @return this (for chained invocation)
-     */
     public ModifyableColumnFamilyDescriptor setBlocksize(int s) {
       return setValue(BLOCKSIZE_BYTES, Integer.toString(s));
     }
@@ -910,6 +892,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the inMemory flag
      * @param inMemory True if we are to favor keeping all values for this column family in the
      *                 HRegionServer cache
      * @return this (for chained invocation)
@@ -924,10 +907,6 @@ public class ColumnFamilyDescriptorBuilder {
         n -> MemoryCompactionPolicy.valueOf(n.toUpperCase()), null);
     }
 
-    /**
-     * @param inMemoryCompaction the prefered in-memory compaction policy for this column family
-     * @return this (for chained invocation)
-     */
     public ModifyableColumnFamilyDescriptor
       setInMemoryCompaction(MemoryCompactionPolicy inMemoryCompaction) {
       return setValue(IN_MEMORY_COMPACTION_BYTES, inMemoryCompaction.name());
@@ -939,10 +918,6 @@ public class ColumnFamilyDescriptorBuilder {
         DEFAULT_KEEP_DELETED);
     }
 
-    /**
-     * @param keepDeletedCells True if deleted rows should not be collected immediately.
-     * @return this (for chained invocation)
-     */
     public ModifyableColumnFamilyDescriptor setKeepDeletedCells(KeepDeletedCells keepDeletedCells) {
       return setValue(KEEP_DELETED_CELLS_BYTES, keepDeletedCells.name());
     }
@@ -968,6 +943,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the time to live
      * @param timeToLive Time-to-live of cell contents, in seconds.
      * @return this (for chained invocation)
      */
@@ -976,9 +952,10 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the time to live
      * @param timeToLive Time-to-live of cell contents, in seconds.
      * @return this (for chained invocation)
-     * @throws org.apache.hadoop.hbase.exceptions.HBaseException
+     * @throws org.apache.hadoop.hbase.exceptions.HBaseException exception
      */
     public ModifyableColumnFamilyDescriptor setTimeToLive(String timeToLive) throws HBaseException {
       return setTimeToLive(Integer.parseInt(PrettyPrinter.valueOf(timeToLive, Unit.TIME_INTERVAL)));
@@ -990,6 +967,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set minimum versions to retain.
      * @param minVersions The minimum number of versions to keep. (used when timeToLive is set)
      * @return this (for chained invocation)
      */
@@ -1019,6 +997,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the blockCacheEnabled flag
      * @param blockCacheEnabled True if hfile DATA type blocks should be cached (We always cache
      *                          INDEX and BLOOM blocks; you cannot turn this off).
      * @return this (for chained invocation)
@@ -1043,10 +1022,6 @@ public class ColumnFamilyDescriptorBuilder {
         DEFAULT_REPLICATION_SCOPE);
     }
 
-    /**
-     * @param scope the scope tag
-     * @return this (for chained invocation)
-     */
     public ModifyableColumnFamilyDescriptor setScope(int scope) {
       return setValue(REPLICATION_SCOPE_BYTES, Integer.toString(scope));
     }
@@ -1058,6 +1033,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the setCacheDataOnWrite flag
      * @param value true if we should cache data blocks on write
      * @return this (for chained invocation)
      */
@@ -1072,6 +1048,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the setCacheIndexesOnWrite flag
      * @param value true if we should cache index blocks on write
      * @return this (for chained invocation)
      */
@@ -1086,6 +1063,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the setCacheBloomsOnWrite flag.
      * @param value true if we should cache bloomfilter blocks on write
      * @return this (for chained invocation)
      */
@@ -1100,6 +1078,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the setEvictBlocksOnClose flag.
      * @param value true if we should evict cached blocks from the blockcache on close
      * @return this (for chained invocation)
      */
@@ -1114,6 +1093,7 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
+     * Set the setPrefetchBlocksOnOpen flag
      * @param value true if we should prefetch blocks into the blockcache on open
      * @return this (for chained invocation)
      */
@@ -1241,19 +1221,17 @@ public class ColumnFamilyDescriptorBuilder {
       return COMPARATOR.compare(this, other);
     }
 
-    /**
-     * @return This instance serialized with pb with pb magic prefix
-     * @see #parseFrom(byte[])
-     */
+    /** Returns This instance serialized with pb with pb magic prefix */
     private byte[] toByteArray() {
       return ProtobufUtil.prependPBMagic(ProtobufUtil.toColumnFamilySchema(this).toByteArray());
     }
 
     /**
+     * Parse the serialized representation of a {@link ModifyableColumnFamilyDescriptor}
      * @param bytes A pb serialized {@link ModifyableColumnFamilyDescriptor} instance with pb magic
      *              prefix
      * @return An instance of {@link ModifyableColumnFamilyDescriptor} made from <code>bytes</code>
-     *         n * @see #toByteArray()
+     * @see #toByteArray()
      */
     private static ColumnFamilyDescriptor parseFrom(final byte[] bytes)
       throws DeserializationException {
@@ -1299,8 +1277,8 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
-     * Remove a configuration setting represented by the key from the {@link #configuration} map. n
-     * * @return this (for chained invocation)
+     * Remove a configuration setting represented by the key from the {@link #configuration} map.
+     * @return this (for chained invocation)
      */
     public ModifyableColumnFamilyDescriptor removeConfiguration(final String key) {
       return setConfiguration(key, null);
@@ -1312,8 +1290,8 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
-     * Set the encryption algorithm for use with this family n * @return this (for chained
-     * invocation)
+     * Set the encryption algorithm for use with this family
+     * @return this (for chained invocation)
      */
     public ModifyableColumnFamilyDescriptor setEncryptionType(String algorithm) {
       return setValue(ENCRYPTION_BYTES, algorithm);
@@ -1325,7 +1303,8 @@ public class ColumnFamilyDescriptorBuilder {
     }
 
     /**
-     * Set the raw crypto key attribute for the family n * @return this (for chained invocation)
+     * Set the raw crypto key attribute for the family
+     * @return this (for chained invocation)
      */
     public ModifyableColumnFamilyDescriptor setEncryptionKey(byte[] keyBytes) {
       return setValue(ENCRYPTION_KEY_BYTES, new Bytes(keyBytes));
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CompactType.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CompactType.java
index 225bb072db7..412fd76d9ec 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CompactType.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/CompactType.java
@@ -26,9 +26,7 @@ import org.apache.yetus.audience.InterfaceAudience;
 @InterfaceAudience.Public
 public enum CompactType {
 
-  NORMAL(0),
-  MOB(1);
+  NORMAL,
+  MOB
 
-  CompactType(int value) {
-  }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionImplementation.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionImplementation.java
index bf97b71b137..8759adc2e97 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionImplementation.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionImplementation.java
@@ -189,9 +189,13 @@ public class ConnectionImplementation implements ClusterConnection, Closeable {
   final int rpcTimeout;
 
   /**
-   * Global nonceGenerator shared per client.Currently there's no reason to limit its scope. Once
+   * Global nonceGenerator shared per client. Currently there's no reason to limit its scope. Once
    * it's set under nonceGeneratorCreateLock, it is never unset or changed.
    */
+  // XXX: It is a bad pattern to assign a value to a static field from a constructor. However
+  // it would likely change semantics if we change it because the NonceGenerator is selected
+  // from configuration passed in as a parameter of the constructor. This has been cleaned up
+  // in later branches.
   private static volatile NonceGenerator nonceGenerator = null;
   /** The nonce generator lock. Only taken when creating Connection, which gets a private copy. */
   private static final Object nonceGeneratorCreateLock = new Object();
@@ -294,7 +298,7 @@ public class ConnectionImplementation implements ClusterConnection, Closeable {
     }
 
     this.stats = ServerStatisticTracker.create(conf);
-    this.interceptor = (new RetryingCallerInterceptorFactory(conf)).build();
+    this.interceptor = new RetryingCallerInterceptorFactory(conf).build();
     this.rpcControllerFactory = RpcControllerFactory.instantiate(conf);
     this.rpcCallerFactory = RpcRetryingCallerFactory.instantiate(conf, interceptor, this.stats);
     this.backoffPolicy = ClientBackoffPolicyFactory.create(conf);
@@ -1186,6 +1190,7 @@ public class ConnectionImplementation implements ClusterConnection, Closeable {
      * @param timeout  how long to wait before timeout, in unit of millisecond
      * @param maxTries how many times to try
      */
+    @SuppressWarnings("JavaUtilDate")
     public ServerErrorTracker(long timeout, int maxTries) {
       this.maxTries = maxTries;
       this.canRetryUntil = EnvironmentEdgeManager.currentTime() + timeout;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java
index 40d16fec49a..aaeece8d8fc 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java
@@ -97,6 +97,7 @@ public final class ConnectionUtils {
   }
 
   /**
+   * Inject a nonce generator for testing.
    * @param conn The connection for which to replace the generator.
    * @param cnm  Replaces the nonce generator used, for testing.
    * @return old nonce generator.
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Delete.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Delete.java
index d2674254752..66716bea9cc 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Delete.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Delete.java
@@ -109,8 +109,6 @@ public class Delete extends Mutation {
    * <p>
    * This timestamp is ONLY used for a delete row operation. If specifying families or columns, you
    * must specify each timestamp individually.
-   * @param row We make a local copy of this passed in row. nn * @param timestamp maximum version
-   *            timestamp (only for delete row)
    */
   public Delete(final byte[] row, final int rowOffset, final int rowLength, long timestamp) {
     checkRow(row, rowOffset, rowLength);
@@ -119,6 +117,7 @@ public class Delete extends Mutation {
   }
 
   /**
+   * Create a Delete operation using another Delete as template.
    * @param deleteToCopy delete to copy
    */
   public Delete(final Delete deleteToCopy) {
@@ -154,6 +153,7 @@ public class Delete extends Mutation {
    * @param cell An existing cell of type "delete".
    * @return this for invocation chaining n
    */
+  @Override
   public Delete add(Cell cell) throws IOException {
     super.add(cell);
     return this;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Get.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Get.java
index 0672faeb73e..1128015d459 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Get.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Get.java
@@ -509,7 +509,7 @@ public class Get extends Query implements Row {
     if (this == obj) {
       return true;
     }
-    if (obj == null || getClass() != obj.getClass()) {
+    if (!(obj instanceof Row)) {
       return false;
     }
     Row other = (Row) obj;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java
index 90b499e416c..e3392d7dfce 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java
@@ -30,7 +30,6 @@ import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Iterator;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -46,7 +45,6 @@ import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.hbase.Abortable;
 import org.apache.hadoop.hbase.CacheEvictionStats;
 import org.apache.hadoop.hbase.CacheEvictionStatsBuilder;
 import org.apache.hadoop.hbase.ClusterMetrics;
@@ -782,7 +780,7 @@ public class HBaseAdmin implements Admin {
    */
   @Override
   public HTableDescriptor[] deleteTables(Pattern pattern) throws IOException {
-    List<HTableDescriptor> failed = new LinkedList<>();
+    List<HTableDescriptor> failed = new ArrayList<>();
     for (HTableDescriptor table : listTables(pattern)) {
       try {
         deleteTable(table.getTableName());
@@ -900,7 +898,7 @@ public class HBaseAdmin implements Admin {
 
   @Override
   public HTableDescriptor[] enableTables(Pattern pattern) throws IOException {
-    List<HTableDescriptor> failed = new LinkedList<>();
+    List<HTableDescriptor> failed = new ArrayList<>();
     for (HTableDescriptor table : listTables(pattern)) {
       if (isTableDisabled(table.getTableName())) {
         try {
@@ -960,7 +958,7 @@ public class HBaseAdmin implements Admin {
 
   @Override
   public HTableDescriptor[] disableTables(Pattern pattern) throws IOException {
-    List<HTableDescriptor> failed = new LinkedList<>();
+    List<HTableDescriptor> failed = new ArrayList<>();
     for (HTableDescriptor table : listTables(pattern)) {
       if (isTableEnabled(table.getTableName())) {
         try {
@@ -1455,6 +1453,7 @@ public class HBaseAdmin implements Admin {
     move(encodedRegionName, (ServerName) null);
   }
 
+  @Override
   public void move(final byte[] encodedRegionName, ServerName destServerName) throws IOException {
     executeCallable(new MasterCallable<Void>(getConnection(), getRpcControllerFactory()) {
       @Override
@@ -1557,7 +1556,7 @@ public class HBaseAdmin implements Admin {
       MetaTableAccessor.getTableRegionsAndLocations(connection, tableName);
     Map<ServerName,
       List<RegionInfo>> regionInfoByServerName = pairs.stream()
-        .filter(pair -> !(pair.getFirst().isOffline())).filter(pair -> pair.getSecond() != null)
+        .filter(pair -> !pair.getFirst().isOffline()).filter(pair -> pair.getSecond() != null)
         .collect(Collectors.groupingBy(pair -> pair.getSecond(),
           Collectors.mapping(pair -> pair.getFirst(), Collectors.toList())));
 
@@ -2836,7 +2835,7 @@ public class HBaseAdmin implements Admin {
 
   @Override
   public List<SnapshotDescription> listSnapshots(Pattern pattern) throws IOException {
-    List<SnapshotDescription> matched = new LinkedList<>();
+    List<SnapshotDescription> matched = new ArrayList<>();
     List<SnapshotDescription> snapshots = listSnapshots();
     for (SnapshotDescription snapshot : snapshots) {
       if (pattern.matcher(snapshot.getName()).matches()) {
@@ -2857,7 +2856,7 @@ public class HBaseAdmin implements Admin {
     Pattern snapshotNamePattern) throws IOException {
     TableName[] tableNames = listTableNames(tableNamePattern);
 
-    List<SnapshotDescription> tableSnapshots = new LinkedList<>();
+    List<SnapshotDescription> tableSnapshots = new ArrayList<>();
     List<SnapshotDescription> snapshots = listSnapshots(snapshotNamePattern);
 
     List<TableName> listOfTableNames = Arrays.asList(tableNames);
@@ -2959,7 +2958,7 @@ public class HBaseAdmin implements Admin {
 
   @Override
   public List<QuotaSettings> getQuota(QuotaFilter filter) throws IOException {
-    List<QuotaSettings> quotas = new LinkedList<>();
+    List<QuotaSettings> quotas = new ArrayList<>();
     try (QuotaRetriever retriever = QuotaRetriever.open(conf, filter)) {
       Iterator<QuotaSettings> iterator = retriever.iterator();
       while (iterator.hasNext()) {
@@ -3017,21 +3016,6 @@ public class HBaseAdmin implements Admin {
     };
   }
 
-  /**
-   * Simple {@link Abortable}, throwing RuntimeException on abort.
-   */
-  private static class ThrowableAbortable implements Abortable {
-    @Override
-    public void abort(String why, Throwable e) {
-      throw new RuntimeException(why, e);
-    }
-
-    @Override
-    public boolean isAborted() {
-      return true;
-    }
-  }
-
   @Override
   public CoprocessorRpcChannel coprocessorService(final ServerName serverName) {
     return new SyncCoprocessorRpcChannel() {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HRegionLocator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HRegionLocator.java
index 7dd59c90961..50e4a26c07c 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HRegionLocator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HRegionLocator.java
@@ -131,6 +131,7 @@ public class HRegionLocator implements RegionLocator {
     return this.tableName;
   }
 
+  @SuppressWarnings("MixedMutabilityReturnType")
   private List<RegionLocations> listRegionLocations() throws IOException {
     if (TableName.isMetaTableName(tableName)) {
       return Collections
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTable.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTable.java
index acb5c9fda5d..f36c4af0de0 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTable.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTable.java
@@ -53,7 +53,6 @@ import org.apache.hadoop.hbase.HRegionLocation;
 import org.apache.hadoop.hbase.HTableDescriptor;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.client.coprocessor.Batch;
-import org.apache.hadoop.hbase.client.coprocessor.Batch.Callback;
 import org.apache.hadoop.hbase.client.trace.TableOperationSpanBuilder;
 import org.apache.hadoop.hbase.client.trace.TableSpanBuilder;
 import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp;
@@ -481,8 +480,8 @@ public class HTable implements Table {
   }
 
   public static <R> void doBatchWithCallback(List<? extends Row> actions, Object[] results,
-    Callback<R> callback, ClusterConnection connection, ExecutorService pool, TableName tableName)
-    throws InterruptedIOException, RetriesExhaustedWithDetailsException {
+    Batch.Callback<R> callback, ClusterConnection connection, ExecutorService pool,
+    TableName tableName) throws InterruptedIOException, RetriesExhaustedWithDetailsException {
     int operationTimeout = connection.getConnectionConfiguration().getOperationTimeout();
     int writeTimeout = connection.getConfiguration().getInt(HConstants.HBASE_RPC_WRITE_TIMEOUT_KEY,
       connection.getConfiguration().getInt(HConstants.HBASE_RPC_TIMEOUT_KEY,
@@ -1264,7 +1263,7 @@ public class HTable implements Table {
   @Override
   public <R extends Message> void batchCoprocessorService(
     final Descriptors.MethodDescriptor methodDescriptor, final Message request, byte[] startKey,
-    byte[] endKey, final R responsePrototype, final Callback<R> callback)
+    byte[] endKey, final R responsePrototype, final Batch.Callback<R> callback)
     throws ServiceException, Throwable {
     final Supplier<Span> supplier = new TableOperationSpanBuilder(connection)
       .setTableName(tableName).setOperation(HBaseSemanticAttributes.Operation.COPROC_EXEC);
@@ -1310,7 +1309,7 @@ public class HTable implements Table {
         RpcRetryingCallerFactory.instantiate(configuration, connection.getStatisticsTracker()),
         RpcControllerFactory.instantiate(configuration));
 
-      Callback<ClientProtos.CoprocessorServiceResult> resultsCallback =
+      Batch.Callback<ClientProtos.CoprocessorServiceResult> resultsCallback =
         (byte[] region, byte[] row, ClientProtos.CoprocessorServiceResult serviceResult) -> {
           if (LOG.isTraceEnabled()) {
             LOG.trace("Received result for endpoint {}: region={}, row={}, value={}",
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTableMultiplexer.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTableMultiplexer.java
index 7404d460b55..ddfe7ca439a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTableMultiplexer.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/HTableMultiplexer.java
@@ -222,6 +222,7 @@ public class HTableMultiplexer {
   }
 
   @InterfaceAudience.Private
+  @SuppressWarnings("FutureReturnValueIgnored")
   LinkedBlockingQueue<PutStatus> getQueue(HRegionLocation addr) {
     FlushWorker worker = serverToFlushWorkerMap.get(addr);
     if (worker == null) {
@@ -455,6 +456,7 @@ public class HTableMultiplexer {
       return this.maxLatency.getAndSet(0);
     }
 
+    @SuppressWarnings("FutureReturnValueIgnored")
     boolean resubmitFailedPut(PutStatus ps, HRegionLocation oldLoc) throws IOException {
       // Decrease the retry count
       final int retryCount = ps.maxAttempCount - 1;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Increment.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Increment.java
index 0efd71e69d2..86c0b65cc43 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Increment.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Increment.java
@@ -94,6 +94,7 @@ public class Increment extends Mutation {
    * Add the specified KeyValue to this operation.
    * @param cell individual Cell n * @throws java.io.IOException e
    */
+  @Override
   public Increment add(Cell cell) throws IOException {
     super.add(cell);
     return this;
@@ -274,7 +275,7 @@ public class Increment extends Mutation {
     if (this == obj) {
       return true;
     }
-    if (obj == null || getClass() != obj.getClass()) {
+    if (!(obj instanceof Increment)) {
       return false;
     }
     Row other = (Row) obj;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/IsolationLevel.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/IsolationLevel.java
index 7804e48de9f..3f94fc30f9c 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/IsolationLevel.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/IsolationLevel.java
@@ -29,11 +29,8 @@ import org.apache.yetus.audience.InterfaceAudience;
 @InterfaceAudience.Public
 public enum IsolationLevel {
 
-  READ_COMMITTED(1),
-  READ_UNCOMMITTED(2);
-
-  IsolationLevel(int value) {
-  }
+  READ_COMMITTED,
+  READ_UNCOMMITTED;
 
   public byte[] toBytes() {
     return new byte[] { toByte() };
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/LogQueryFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/LogQueryFilter.java
index b2d217da3de..61137076a12 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/LogQueryFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/LogQueryFilter.java
@@ -112,13 +112,10 @@ public class LogQueryFilter {
     if (this == o) {
       return true;
     }
-
-    if (o == null || getClass() != o.getClass()) {
+    if (!(o instanceof LogQueryFilter)) {
       return false;
     }
-
     LogQueryFilter that = (LogQueryFilter) o;
-
     return new EqualsBuilder().append(limit, that.limit).append(regionName, that.regionName)
       .append(clientAddress, that.clientAddress).append(tableName, that.tableName)
       .append(userName, that.userName).append(type, that.type)
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterCoprocessorRpcChannelImpl.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterCoprocessorRpcChannelImpl.java
index c6f0ceec550..e315e56ed27 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterCoprocessorRpcChannelImpl.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterCoprocessorRpcChannelImpl.java
@@ -77,11 +77,11 @@ class MasterCoprocessorRpcChannelImpl implements RpcChannel {
     Message responsePrototype, RpcCallback<Message> done) {
     addListener(
       callerBuilder.action((c, s) -> rpcCall(method, request, responsePrototype, c, s)).call(),
-      ((r, e) -> {
+      (r, e) -> {
         if (e != null) {
           ((ClientCoprocessorRpcController) controller).setFailed(e);
         }
         done.run(r);
-      }));
+      });
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterRegistry.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterRegistry.java
index a031d353097..28ac5bb4528 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterRegistry.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterRegistry.java
@@ -34,6 +34,7 @@ import org.apache.hadoop.hbase.util.DNS.ServerType;
 import org.apache.yetus.audience.InterfaceAudience;
 
 import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
+import org.apache.hbase.thirdparty.com.google.common.base.Splitter;
 import org.apache.hbase.thirdparty.com.google.common.base.Strings;
 import org.apache.hbase.thirdparty.com.google.common.net.HostAndPort;
 
@@ -78,7 +79,8 @@ public class MasterRegistry extends AbstractRpcBasedConnectionRegistry {
   public static Set<ServerName> parseMasterAddrs(Configuration conf) throws UnknownHostException {
     Set<ServerName> masterAddrs = new HashSet<>();
     String configuredMasters = getMasterAddr(conf);
-    for (String masterAddr : configuredMasters.split(MASTER_ADDRS_CONF_SEPARATOR)) {
+    for (String masterAddr : Splitter.onPattern(MASTER_ADDRS_CONF_SEPARATOR)
+      .split(configuredMasters)) {
       HostAndPort masterHostPort =
         HostAndPort.fromString(masterAddr.trim()).withDefaultPort(HConstants.DEFAULT_MASTER_PORT);
       masterAddrs.add(ServerName.valueOf(masterHostPort.toString(), ServerName.NON_STARTCODE));
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiAction.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiAction.java
index cc3db106c4e..fbb1824595f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiAction.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiAction.java
@@ -36,8 +36,10 @@ import org.apache.yetus.audience.InterfaceAudience;
 public final class MultiAction {
   // TODO: This class should not be visible outside of the client package.
 
-  // map of regions to lists of puts/gets/deletes for that region.
-  protected Map<byte[], List<Action>> actions = new TreeMap<>(Bytes.BYTES_COMPARATOR);
+  /**
+   * A map of regions to lists of puts/gets/deletes for that region. Package visible.
+   */
+  Map<byte[], List<Action>> actions = new TreeMap<>(Bytes.BYTES_COMPARATOR);
 
   private long nonceGroup = HConstants.NO_NONCE;
 
@@ -60,7 +62,7 @@ public final class MultiAction {
   /**
    * Add an Action to this container based on it's regionName. If the regionName is wrong, the
    * initial execution will fail, but will be automatically retried after looking up the correct
-   * region. nn
+   * region.
    */
   public void add(byte[] regionName, Action a) {
     add(regionName, Collections.singletonList(a));
@@ -69,7 +71,7 @@ public final class MultiAction {
   /**
    * Add an Action to this container based on it's regionName. If the regionName is wrong, the
    * initial execution will fail, but will be automatically retried after looking up the correct
-   * region. n * @param actionList list of actions to add for the region
+   * region.
    */
   public void add(byte[] regionName, List<Action> actionList) {
     List<Action> rsActions = actions.get(regionName);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiResponse.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiResponse.java
index b768b76fdb6..341341b4336 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiResponse.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiResponse.java
@@ -53,11 +53,7 @@ public class MultiResponse extends AbstractResponse {
     return size;
   }
 
-  /**
-   * Add the pair to the container, grouped by the regionName n * @param originalIndex the original
-   * index of the Action (request).
-   * @param resOrEx the result or error; will be empty for successful Put and Delete actions.
-   */
+  /** Add the pair to the container, grouped by the regionName. */
   public void add(byte[] regionName, int originalIndex, Object resOrEx) {
     getResult(regionName).addResult(originalIndex, resOrEx);
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiServerCallable.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiServerCallable.java
index 6484235b1eb..86b499ea567 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiServerCallable.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MultiServerCallable.java
@@ -44,7 +44,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.RegionActi
  * Callable that handles the <code>multi</code> method call going against a single regionserver;
  * i.e. A RegionServerCallable for the multi call (It is NOT a RegionServerCallable that goes
  * against multiple regions).
- * @param <R>
  */
 @InterfaceAudience.Private
 class MultiServerCallable extends CancellableRegionServerCallable<MultiResponse> {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MutableRegionInfo.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MutableRegionInfo.java
index 7627f8dc0e5..fbb76ea4f65 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MutableRegionInfo.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MutableRegionInfo.java
@@ -230,6 +230,7 @@ class MutableRegionInfo implements RegionInfo {
   }
 
   /**
+   * Change the split status flag.
    * @param split set split status n
    */
   public MutableRegionInfo setSplit(boolean split) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Mutation.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Mutation.java
index 408b02e44fa..ac1e9fce079 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Mutation.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Mutation.java
@@ -152,7 +152,7 @@ public abstract class Mutation extends OperationWithAttributes
     return list;
   }
 
-  /*
+  /**
    * Create a KeyValue with this objects row key and the Put identifier.
    * @return a KeyValue with this objects row key and the Put identifier.
    */
@@ -161,8 +161,7 @@ public abstract class Mutation extends OperationWithAttributes
   }
 
   /**
-   * Create a KeyValue with this objects row key and the Put identifier. nnnn * @param tags -
-   * Specify the Tags as an Array
+   * Create a KeyValue with this objects row key and the Put identifier.
    * @return a KeyValue with this objects row key and the Put identifier.
    */
   KeyValue createPutKeyValue(byte[] family, byte[] qualifier, long ts, byte[] value, Tag[] tags) {
@@ -170,7 +169,7 @@ public abstract class Mutation extends OperationWithAttributes
     return kvWithTag;
   }
 
-  /*
+  /**
    * Create a KeyValue with this objects row key and the Put identifier.
    * @return a KeyValue with this objects row key and the Put identifier.
    */
@@ -183,7 +182,7 @@ public abstract class Mutation extends OperationWithAttributes
 
   /**
    * Compile the column family (i.e. schema) information into a Map. Useful for parsing and
-   * aggregation by debugging, logging, and administration tools. n
+   * aggregation by debugging, logging, and administration tools.
    */
   @Override
   public Map<String, Object> getFingerprint() {
@@ -257,7 +256,7 @@ public abstract class Mutation extends OperationWithAttributes
     if (tags != null) {
       List<String> tagsString = new ArrayList<>(tags.size());
       for (Tag t : tags) {
-        tagsString.add((t.getType()) + ":" + Bytes.toStringBinary(Tag.cloneValue(t)));
+        tagsString.add(t.getType() + ":" + Bytes.toStringBinary(Tag.cloneValue(t)));
       }
       stringMap.put("tag", tagsString);
     }
@@ -473,6 +472,7 @@ public abstract class Mutation extends OperationWithAttributes
   }
 
   /**
+   * Set the ACL for this operation.
    * @param user  User short name
    * @param perms Permissions for the user
    */
@@ -483,6 +483,7 @@ public abstract class Mutation extends OperationWithAttributes
   }
 
   /**
+   * Set the ACL for this operation.
    * @param perms A map of permissions for a user or users
    */
   public Mutation setACL(Map<String, Permission> perms) {
@@ -624,11 +625,9 @@ public abstract class Mutation extends OperationWithAttributes
     return filteredList;
   }
 
-  /*
+  /**
    * Private method to determine if this object's familyMap contains the given value assigned to the
-   * given family, qualifier and timestamp respecting the 2 boolean arguments nnnnnn * @return
-   * returns true if the given family, qualifier timestamp and value already has an existing
-   * KeyValue object in the family map.
+   * given family, qualifier and timestamp, respecting the 2 boolean arguments.
    */
   protected boolean has(byte[] family, byte[] qualifier, long ts, byte[] value, boolean ignoreTS,
     boolean ignoreValue) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/PreemptiveFastFailInterceptor.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/PreemptiveFastFailInterceptor.java
index 0223109c4e8..edca3c7b6b6 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/PreemptiveFastFailInterceptor.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/PreemptiveFastFailInterceptor.java
@@ -86,7 +86,8 @@ class PreemptiveFastFailInterceptor extends RetryingCallerInterceptor {
   // fast fail mode for any reason.
   private long fastFailClearingTimeMilliSec;
 
-  private final ThreadLocal<MutableBoolean> threadRetryingInFastFailMode = new ThreadLocal<>();
+  private static final ThreadLocal<MutableBoolean> threadRetryingInFastFailMode =
+    new ThreadLocal<>();
 
   public PreemptiveFastFailInterceptor(Configuration conf) {
     this.fastFailThresholdMilliSec = conf.getLong(HConstants.HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS,
@@ -216,8 +217,8 @@ class PreemptiveFastFailInterceptor extends RetryingCallerInterceptor {
    * @return true, if the thread is already in FF mode.
    */
   private boolean currentThreadInFastFailMode() {
-    return (this.threadRetryingInFastFailMode.get() != null
-      && (this.threadRetryingInFastFailMode.get().booleanValue() == true));
+    return (threadRetryingInFastFailMode.get() != null
+      && (threadRetryingInFastFailMode.get().booleanValue() == true));
   }
 
   /**
@@ -232,10 +233,10 @@ class PreemptiveFastFailInterceptor extends RetryingCallerInterceptor {
     // actively trying to connect. If we are the chosen one, we will retry
     // and not throw an exception.
     if (fInfo != null && fInfo.exclusivelyRetringInspiteOfFastFail.compareAndSet(false, true)) {
-      MutableBoolean threadAlreadyInFF = this.threadRetryingInFastFailMode.get();
+      MutableBoolean threadAlreadyInFF = threadRetryingInFastFailMode.get();
       if (threadAlreadyInFF == null) {
         threadAlreadyInFF = new MutableBoolean();
-        this.threadRetryingInFastFailMode.set(threadAlreadyInFF);
+        threadRetryingInFastFailMode.set(threadAlreadyInFF);
       }
       threadAlreadyInFF.setValue(true);
       return true;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Put.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Put.java
index a3502f29bd0..df26f091ff7 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Put.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Put.java
@@ -257,6 +257,7 @@ public class Put extends Mutation implements HeapSize {
    * immutable and its backing array will not be modified for the duration of this Put.
    * @param cell individual cell n * @throws java.io.IOException e
    */
+  @Override
   public Put add(Cell cell) throws IOException {
     super.add(cell);
     return this;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Query.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Query.java
index d752693dabc..a954d84db0e 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Query.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Query.java
@@ -88,6 +88,7 @@ public abstract class Query extends OperationWithAttributes {
   }
 
   /**
+   * Set the ACL for the operation.
    * @param user  User short name
    * @param perms Permissions for the user
    */
@@ -98,6 +99,7 @@ public abstract class Query extends OperationWithAttributes {
   }
 
   /**
+   * Set the ACL for the operation.
    * @param perms A map of permissions for a user or users
    */
   public Query setACL(Map<String, Permission> perms) {
@@ -159,9 +161,8 @@ public abstract class Query extends OperationWithAttributes {
   }
 
   /**
-   * @return The isolation level of this query. If no isolation level was set for this query object,
-   *         then it returns READ_COMMITTED.
-   * @return The IsolationLevel for this query
+   * Returns The isolation level of this query. If no isolation level was set for this query object,
+   * then it returns READ_COMMITTED.
    */
   public IsolationLevel getIsolationLevel() {
     byte[] attr = getAttribute(ISOLATION_LEVEL);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java
index 8634f33c163..a310e7d864f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncHBaseAdmin.java
@@ -469,11 +469,6 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
     return future;
   }
 
-  @FunctionalInterface
-  private interface TableOperator {
-    CompletableFuture<Void> operate(TableName table);
-  }
-
   @Override
   public CompletableFuture<Boolean> tableExists(TableName tableName) {
     if (TableName.isMetaTableName(tableName)) {
@@ -1539,11 +1534,13 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
         future.completeExceptionally(err);
         return;
       }
-      addListener(this.<Void> newMasterCaller().priority(regionInfo.getTable())
-        .action(((controller, stub) -> this.<AssignRegionRequest, AssignRegionResponse, Void> call(
-          controller, stub, RequestConverter.buildAssignRegionRequest(regionInfo.getRegionName()),
-          (s, c, req, done) -> s.assignRegion(c, req, done), resp -> null)))
-        .call(), (ret, err2) -> {
+      addListener(
+        this.<Void> newMasterCaller().priority(regionInfo.getTable())
+          .action((controller, stub) -> this.<AssignRegionRequest, AssignRegionResponse, Void> call(
+            controller, stub, RequestConverter.buildAssignRegionRequest(regionInfo.getRegionName()),
+            (s, c, req, done) -> s.assignRegion(c, req, done), resp -> null))
+          .call(),
+        (ret, err2) -> {
           if (err2 != null) {
             future.completeExceptionally(err2);
           } else {
@@ -1564,10 +1561,10 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
       }
       addListener(
         this.<Void> newMasterCaller().priority(regionInfo.getTable())
-          .action(((controller, stub) -> this.<UnassignRegionRequest, UnassignRegionResponse,
+          .action((controller, stub) -> this.<UnassignRegionRequest, UnassignRegionResponse,
             Void> call(controller, stub,
               RequestConverter.buildUnassignRegionRequest(regionInfo.getRegionName()),
-              (s, c, req, done) -> s.unassignRegion(c, req, done), resp -> null)))
+              (s, c, req, done) -> s.unassignRegion(c, req, done), resp -> null))
           .call(),
         (ret, err2) -> {
           if (err2 != null) {
@@ -1588,14 +1585,11 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
         future.completeExceptionally(err);
         return;
       }
-      addListener(
-        this.<Void> newMasterCaller().priority(regionInfo.getTable())
-          .action(((controller, stub) -> this.<OfflineRegionRequest, OfflineRegionResponse,
-            Void> call(controller, stub,
-              RequestConverter.buildOfflineRegionRequest(regionInfo.getRegionName()),
-              (s, c, req, done) -> s.offlineRegion(c, req, done), resp -> null)))
-          .call(),
-        (ret, err2) -> {
+      addListener(this.<Void> newMasterCaller().priority(regionInfo.getTable())
+        .action((controller, stub) -> this.<OfflineRegionRequest, OfflineRegionResponse, Void> call(
+          controller, stub, RequestConverter.buildOfflineRegionRequest(regionInfo.getRegionName()),
+          (s, c, req, done) -> s.offlineRegion(c, req, done), resp -> null))
+        .call(), (ret, err2) -> {
           if (err2 != null) {
             future.completeExceptionally(err2);
           } else {
@@ -2206,7 +2200,7 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
       listSnapshotsFuture = getCompletedSnapshots(tableNamePattern, snapshotNamePattern);
     }
     CompletableFuture<Void> future = new CompletableFuture<>();
-    addListener(listSnapshotsFuture, ((snapshotDescriptions, err) -> {
+    addListener(listSnapshotsFuture, (snapshotDescriptions, err) -> {
       if (err != null) {
         future.completeExceptionally(err);
         return;
@@ -2223,7 +2217,7 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
             future.complete(v);
           }
         });
-    }));
+    });
     return future;
   }
 
@@ -3966,9 +3960,9 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
 
   private CompletableFuture<Boolean> clearSlowLogsResponses(final ServerName serverName) {
     return this.<Boolean> newAdminCaller()
-      .action(((controller, stub) -> this.adminCall(controller, stub,
+      .action((controller, stub) -> this.adminCall(controller, stub,
         RequestConverter.buildClearSlowLogResponseRequest(),
-        AdminService.Interface::clearSlowLogsResponses, ProtobufUtil::toClearSlowLogPayload)))
+        AdminService.Interface::clearSlowLogsResponses, ProtobufUtil::toClearSlowLogPayload))
       .serverName(serverName).call();
   }
 
@@ -4030,9 +4024,9 @@ class RawAsyncHBaseAdmin implements AsyncAdmin {
   public CompletableFuture<Void> flushMasterStore() {
     FlushMasterStoreRequest.Builder request = FlushMasterStoreRequest.newBuilder();
     return this.<Void> newMasterCaller()
-      .action(((controller, stub) -> this.<FlushMasterStoreRequest, FlushMasterStoreResponse,
+      .action((controller, stub) -> this.<FlushMasterStoreRequest, FlushMasterStoreResponse,
         Void> call(controller, stub, request.build(),
-          (s, c, req, done) -> s.flushMasterStore(c, req, done), resp -> null)))
+          (s, c, req, done) -> s.flushMasterStore(c, req, done), resp -> null))
       .call();
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncTableImpl.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncTableImpl.java
index ccf879f1684..7ffd9eabd7d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncTableImpl.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RawAsyncTableImpl.java
@@ -814,7 +814,7 @@ class RawAsyncTableImpl implements AsyncTable<AdvancedScanResultConsumer> {
       int c = Bytes.compareTo(endKey, region.getEndKey());
       // 1. if the region contains endKey
       // 2. endKey is equal to the region's endKey and we do not want to include endKey.
-      return c < 0 || c == 0 && !endKeyInclusive;
+      return c < 0 || (c == 0 && !endKeyInclusive);
     }
   }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionCoprocessorServiceExec.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionCoprocessorServiceExec.java
index 720e97df636..5c3409813d4 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionCoprocessorServiceExec.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionCoprocessorServiceExec.java
@@ -93,7 +93,7 @@ public class RegionCoprocessorServiceExec implements Row {
     if (this == obj) {
       return true;
     }
-    if (obj == null || getClass() != obj.getClass()) {
+    if (!(obj instanceof RegionCoprocessorServiceExec)) {
       return false;
     }
     return compareTo((RegionCoprocessorServiceExec) obj) == 0;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionInfo.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionInfo.java
index de3f53707b8..88731ab1616 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionInfo.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionInfo.java
@@ -160,7 +160,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   long getRegionId();
 
   /**
-   * @return the regionName as an array of bytes.
+   * Returns the regionName as an array of bytes.
    * @see #getRegionNameAsString()
    */
   byte[] getRegionName();
@@ -190,7 +190,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   boolean isSplit();
 
   /**
-   * @return True if this region is offline.
+   * Returns True if this region is offline.
    * @deprecated since 3.0.0 and will be removed in 4.0.0
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-25210">HBASE-25210</a>
    */
@@ -198,7 +198,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   boolean isOffline();
 
   /**
-   * @return True if this is a split parent region.
+   * Returns True if this is a split parent region.
    * @deprecated since 3.0.0 and will be removed in 4.0.0, Use {@link #isSplit()} instead.
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-25210">HBASE-25210</a>
    */
@@ -209,9 +209,9 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   boolean isMetaRegion();
 
   /**
-   * @return true if the given inclusive range of rows is fully contained by this region. For
-   *         example, if the region is foo,a,g and this is passed ["b","c"] or ["a","c"] it will
-   *         return true, but if this is passed ["b","z"] it will return false.
+   * Returns true if the given inclusive range of rows is fully contained by this region. For
+   * example, if the region is foo,a,g and this is passed ["b","c"] or ["a","c"] it will return
+   * true, but if this is passed ["b","z"] it will return false.
    * @throws IllegalArgumentException if the range passed is invalid (ie. end &lt; start)
    */
   boolean containsRange(byte[] rangeStartKey, byte[] rangeEndKey);
@@ -271,16 +271,16 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   }
 
   /**
-   * @return Return a String of short, printable names for <code>hris</code> (usually encoded name)
-   *         for us logging.
+   * Returns a String of short, printable names for <code>hris</code> (usually encoded name) for us
+   * logging.
    */
   static String getShortNameToLog(RegionInfo... hris) {
     return getShortNameToLog(Arrays.asList(hris));
   }
 
   /**
-   * @return Return a String of short, printable names for <code>hris</code> (usually encoded name)
-   *         for us logging.
+   * Returns a String of short, printable names for <code>hris</code> (usually encoded name) for us
+   * logging.
    */
   static String getShortNameToLog(final List<RegionInfo> ris) {
     return ris.stream().map(RegionInfo::getEncodedName).collect(Collectors.toList()).toString();
@@ -369,8 +369,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   }
 
   /**
-   * @param bytes A pb RegionInfo serialized with a pb magic prefix.
-   * @return A deserialized {@link RegionInfo}
+   * Returns A deserialized {@link RegionInfo}
    */
   @InterfaceAudience.Private
   static RegionInfo parseFrom(final byte[] bytes) throws DeserializationException {
@@ -379,6 +378,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   }
 
   /**
+   * Parse a serialized representation of {@link RegionInfo}
    * @param bytes  A pb RegionInfo serialized with a pb magic prefix.
    * @param offset starting point in the byte array
    * @param len    length to read on the byte array
@@ -437,7 +437,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   }
 
   /**
-   * @return This instance serialized as protobuf w/ a magic pb prefix.
+   * Returns This instance serialized as protobuf w/ a magic pb prefix.
    * @see #parseFrom(byte[])
    */
   static byte[] toByteArray(RegionInfo ri) {
@@ -765,7 +765,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   }
 
   /**
-   * @return True if region is next, adjacent but 'after' this one.
+   * Returns True if region is next, adjacent but 'after' this one.
    * @see #isAdjacent(RegionInfo)
    * @see #areAdjacent(RegionInfo, RegionInfo)
    */
@@ -774,7 +774,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   }
 
   /**
-   * @return True if region is adjacent, either just before or just after this one.
+   * Returns True if region is adjacent, either just before or just after this one.
    * @see #isNext(RegionInfo)
    */
   default boolean isAdjacent(RegionInfo other) {
@@ -787,7 +787,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
   }
 
   /**
-   * @return True if an overlap in region range.
+   * Returns True if an overlap in region range.
    * @see #isDegenerate()
    */
   default boolean isOverlap(RegionInfo other) {
@@ -813,6 +813,7 @@ public interface RegionInfo extends Comparable<RegionInfo> {
     return Bytes.compareTo(getStartKey(), other.getEndKey()) < 0;
   }
 
+  @Override
   default int compareTo(RegionInfo other) {
     return RegionInfo.COMPARATOR.compare(this, other);
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionReplicaUtil.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionReplicaUtil.java
index 4475a01c0f9..1d6708b49d1 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionReplicaUtil.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionReplicaUtil.java
@@ -51,7 +51,7 @@ public class RegionReplicaUtil {
   /**
    * Returns the RegionInfo for the given replicaId. RegionInfo's correspond to a range of a table,
    * but more than one "instance" of the same range can be deployed which are differentiated by the
-   * replicaId. n * @param replicaId the replicaId to use
+   * replicaId.
    * @return an RegionInfo object corresponding to the same range (table, start and end key), but
    *         for the given replicaId.
    */
@@ -149,7 +149,7 @@ public class RegionReplicaUtil {
     if ((newReplicaCount - 1) <= 0) {
       return regions;
     }
-    List<RegionInfo> hRegionInfos = new ArrayList<>((newReplicaCount) * regions.size());
+    List<RegionInfo> hRegionInfos = new ArrayList<>(newReplicaCount * regions.size());
     for (RegionInfo ri : regions) {
       if (
         RegionReplicaUtil.isDefaultReplica(ri)
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionServerCoprocessorRpcChannelImpl.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionServerCoprocessorRpcChannelImpl.java
index 76bca140ef1..7b60777e958 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionServerCoprocessorRpcChannelImpl.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RegionServerCoprocessorRpcChannelImpl.java
@@ -77,11 +77,11 @@ public class RegionServerCoprocessorRpcChannelImpl implements RpcChannel {
     Message responsePrototype, RpcCallback<Message> done) {
     addListener(
       callerBuilder.action((c, s) -> rpcCall(method, request, responsePrototype, c, s)).call(),
-      ((r, e) -> {
+      (r, e) -> {
         if (e != null) {
           ((ClientCoprocessorRpcController) controller).setFailed(e);
         }
         done.run(r);
-      }));
+      });
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Result.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Result.java
index 2ae13c6ce1c..ced6b5ea442 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Result.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Result.java
@@ -873,6 +873,7 @@ public class Result implements CellScannable, CellScanner {
   }
 
   /**
+   * Whether or not the results are partial.
    * @deprecated the word 'partial' ambiguous, use {@link #mayHaveMoreCellsInRow()} instead.
    *             Deprecated since 1.4.0.
    * @see #mayHaveMoreCellsInRow()
@@ -904,8 +905,8 @@ public class Result implements CellScannable, CellScanner {
   }
 
   /**
-   * @return the associated statistics about the region from which this was returned. Can be
-   *         <tt>null</tt> if stats are disabled.
+   * Returns the associated statistics about the region from which this was returned. Can be
+   * <tt>null</tt> if stats are disabled.
    */
   public RegionLoadStats getStats() {
     return stats;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RetryingCallable.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RetryingCallable.java
index 8885069b41a..745aabb143a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RetryingCallable.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RetryingCallable.java
@@ -46,13 +46,14 @@ public interface RetryingCallable<T> {
   void throwable(final Throwable t, boolean retrying);
 
   /**
-   * @return Some details from the implementation that we would like to add to a terminating
-   *         exception; i.e. a fatal exception is being thrown ending retries and we might like to
-   *         add more implementation-specific detail on to the exception being thrown.
+   * Returns Some details from the implementation that we would like to add to a terminating
+   * exception; i.e. a fatal exception is being thrown ending retries and we might like to add more
+   * implementation-specific detail on to the exception being thrown.
    */
   String getExceptionMessageAdditionalDetail();
 
   /**
+   * Sleep and retry.
    * @param pause time to pause
    * @param tries amount of tries until till sleep
    * @return Suggestion on how much to sleep between retries
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Row.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Row.java
index 683304ff758..32d283a2883 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Row.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Row.java
@@ -32,9 +32,11 @@ public interface Row extends Comparable<Row> {
   byte[] getRow();
 
   /**
+   * Compare this row to another row.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0. Use
    *             {@link Row#COMPARATOR} instead
    */
   @Deprecated
+  @Override
   int compareTo(Row var1);
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowAccess.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowAccess.java
index cd1f4756079..1af8798fd87 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowAccess.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowAccess.java
@@ -22,7 +22,6 @@ import org.apache.yetus.audience.InterfaceAudience;
 /**
  * Provide a way to access the inner buffer. The purpose is to reduce the elapsed time to move a
  * large number of elements between collections.
- * @param <T>
  */
 @InterfaceAudience.Private
 public interface RowAccess<T> extends Iterable<T> {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowMutations.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowMutations.java
index 1d9b94a54cc..b5857fb1364 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowMutations.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RowMutations.java
@@ -102,6 +102,7 @@ public class RowMutations implements Row {
   }
 
   /**
+   * Add a list of mutations
    * @param mutations The data to send.
    * @throws IOException if the row of added mutation doesn't match the original row
    */
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerFactory.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerFactory.java
index 19daacd77a7..a1991378228 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerFactory.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerFactory.java
@@ -18,7 +18,6 @@
 package org.apache.hadoop.hbase.client;
 
 import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.util.ReflectionUtils;
 import org.apache.yetus.audience.InterfaceAudience;
 
@@ -34,9 +33,6 @@ public class RpcRetryingCallerFactory {
   private final ConnectionConfiguration connectionConf;
   private final RetryingCallerInterceptor interceptor;
   private final int startLogErrorsCnt;
-  /* These below data members are UNUSED!!! */
-  private final boolean enableBackPressure;
-  private ServerStatisticTracker stats;
 
   public RpcRetryingCallerFactory(Configuration conf) {
     this(conf, RetryingCallerInterceptorFactory.NO_OP_INTERCEPTOR);
@@ -48,15 +44,6 @@ public class RpcRetryingCallerFactory {
     startLogErrorsCnt = conf.getInt(AsyncProcess.START_LOG_ERRORS_AFTER_COUNT_KEY,
       AsyncProcess.DEFAULT_START_LOG_ERRORS_AFTER_COUNT);
     this.interceptor = interceptor;
-    enableBackPressure = conf.getBoolean(HConstants.ENABLE_CLIENT_BACKPRESSURE,
-      HConstants.DEFAULT_ENABLE_CLIENT_BACKPRESSURE);
-  }
-
-  /**
-   * Set the tracker that should be used for tracking statistics about the server
-   */
-  public void setStatisticTracker(ServerStatisticTracker statisticTracker) {
-    this.stats = statisticTracker;
   }
 
   /**
@@ -102,9 +89,6 @@ public class RpcRetryingCallerFactory {
       factory = ReflectionUtils.instantiateWithCustomCtor(rpcCallerFactoryClazz,
         new Class[] { Configuration.class }, new Object[] { configuration });
     }
-
-    // setting for backwards compat with existing caller factories, rather than in the ctor
-    factory.setStatisticTracker(stats);
     return factory;
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerImpl.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerImpl.java
index 2c82cdd54bc..67b12b8a34b 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerImpl.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcRetryingCallerImpl.java
@@ -156,7 +156,7 @@ public class RpcRetryingCallerImpl<T> implements RpcRetryingCaller<T> {
         if (duration > callTimeout) {
           String msg = "callTimeout=" + callTimeout + ", callDuration=" + duration + ": "
             + t.getMessage() + " " + callable.getExceptionMessageAdditionalDetail();
-          throw (SocketTimeoutException) (new SocketTimeoutException(msg).initCause(t));
+          throw (SocketTimeoutException) new SocketTimeoutException(msg).initCause(t);
         }
       } finally {
         interceptor.updateFailureInfo(context);
@@ -235,7 +235,7 @@ public class RpcRetryingCallerImpl<T> implements RpcRetryingCaller<T> {
 
   private int getTimeout(int callTimeout) {
     int timeout = tracker.getRemainingTime(callTimeout);
-    if (timeout <= 0 || rpcTimeout > 0 && rpcTimeout < timeout) {
+    if (timeout <= 0 || (rpcTimeout > 0 && rpcTimeout < timeout)) {
       timeout = rpcTimeout;
     }
     return timeout;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Scan.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Scan.java
index d417d8e8453..44ef44b3b67 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Scan.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Scan.java
@@ -866,9 +866,9 @@ public class Scan extends Query {
   }
 
   /**
-   * @return true when the constructor of this scan understands that the results they will see may
-   *         only represent a partial portion of a row. The entire row would be retrieved by
-   *         subsequent calls to {@link ResultScanner#next()}
+   * Returns true when the constructor of this scan understands that the results they will see may
+   * only represent a partial portion of a row. The entire row would be retrieved by subsequent
+   * calls to {@link ResultScanner#next()}
    */
   public boolean getAllowPartialResults() {
     return allowPartialResults;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScanResultConsumer.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScanResultConsumer.java
index b574b2c2bd5..44f8e194045 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScanResultConsumer.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScanResultConsumer.java
@@ -30,8 +30,7 @@ import org.apache.yetus.audience.InterfaceAudience;
 public interface ScanResultConsumer extends ScanResultConsumerBase {
 
   /**
-   * @param result the data fetched from HBase service.
-   * @return {@code false} if you want to terminate the scan process. Otherwise {@code true}
+   * Return {@code false} if you want to terminate the scan process. Otherwise {@code true}
    */
   boolean onNext(Result result);
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScannerCallableWithReplicas.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScannerCallableWithReplicas.java
index 21653214ce6..fe155136cb2 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScannerCallableWithReplicas.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScannerCallableWithReplicas.java
@@ -262,6 +262,7 @@ class ScannerCallableWithReplicas implements RetryingCallable<Result[]> {
     throw new IOException("Imposible? Arrive at an unreachable line...");
   }
 
+  @SuppressWarnings("FutureReturnValueIgnored")
   private void updateCurrentlyServingReplica(ScannerCallable scanner, Result[] result,
     AtomicBoolean done, ExecutorService pool) {
     if (done.compareAndSet(false, true)) {
@@ -308,10 +309,10 @@ class ScannerCallableWithReplicas implements RetryingCallable<Result[]> {
   }
 
   /**
-   * @return true when the most recent RPC response indicated that the response was a heartbeat
-   *         message. Heartbeat messages are sent back from the server when the processing of the
-   *         scan request exceeds a certain time threshold. Heartbeats allow the server to avoid
-   *         timeouts during long running scan operations.
+   * Returns true when the most recent RPC response indicated that the response was a heartbeat
+   * message. Heartbeat messages are sent back from the server when the processing of the scan
+   * request exceeds a certain time threshold. Heartbeats allow the server to avoid timeouts during
+   * long running scan operations.
    */
   public boolean isHeartbeatMessage() {
     return currentScannerCallable != null && currentScannerCallable.isHeartbeatMessage();
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ServiceCaller.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ServiceCaller.java
index fc550c880a6..626d8675277 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ServiceCaller.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ServiceCaller.java
@@ -27,20 +27,16 @@ import org.apache.yetus.audience.InterfaceAudience;
  * Usually, it is just a simple lambda expression, like:
  *
  * <pre>
- * <code>
- * (stub, controller, rpcCallback) -> {
+ * (stub, controller, rpcCallback) -&gt; {
  *   XXXRequest request = ...; // prepare the request
  *   stub.xxx(controller, request, rpcCallback);
  * }
- * </code>
  * </pre>
  *
  * And if already have the {@code request}, the lambda expression will be:
  *
  * <pre>
- * <code>
- * (stub, controller, rpcCallback) -> stub.xxx(controller, request, rpcCallback)
- * </code>
+ * (stub, controller, rpcCallback) -&gt; stub.xxx(controller, request, rpcCallback)
  * </pre>
  *
  * @param <S> the type of the protobuf Service you want to call.
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SlowLogParams.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SlowLogParams.java
index 3311539c261..b1460c0b116 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SlowLogParams.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SlowLogParams.java
@@ -62,13 +62,10 @@ public class SlowLogParams {
     if (this == o) {
       return true;
     }
-
-    if (o == null || getClass() != o.getClass()) {
+    if (!(o instanceof SlowLogParams)) {
       return false;
     }
-
     SlowLogParams that = (SlowLogParams) o;
-
     return new EqualsBuilder().append(regionName, that.regionName).append(params, that.params)
       .isEquals();
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SnapshotDescription.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SnapshotDescription.java
index 4cf7a876137..a01735955b5 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SnapshotDescription.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/SnapshotDescription.java
@@ -160,6 +160,7 @@ public class SnapshotDescription {
   }
 
   /**
+   * Get the table name as a string.
    * @deprecated since 2.0.0 and will be removed in 3.0.0. Use {@link #getTableName()} or
    *             {@link #getTableNameAsString()} instead.
    * @see #getTableName()
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Table.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Table.java
index 894b4678908..79d3572cd61 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Table.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Table.java
@@ -464,11 +464,13 @@ public interface Table extends Closeable {
   interface CheckAndMutateBuilder {
 
     /**
+     * Specify a column qualifer
      * @param qualifier column qualifier to check.
      */
     CheckAndMutateBuilder qualifier(byte[] qualifier);
 
     /**
+     * Specify a timerange
      * @param timeRange timeRange to check
      */
     CheckAndMutateBuilder timeRange(TimeRange timeRange);
@@ -487,24 +489,28 @@ public interface Table extends Closeable {
     }
 
     /**
+     * Check for match.
      * @param compareOp comparison operator to use
      * @param value     the expected value
      */
     CheckAndMutateBuilder ifMatches(CompareOperator compareOp, byte[] value);
 
     /**
+     * Specify a Put to commit if the check succeeds.
      * @param put data to put if check succeeds
      * @return {@code true} if the new put was executed, {@code false} otherwise.
      */
     boolean thenPut(Put put) throws IOException;
 
     /**
+     * Specify a Delete to commit if the check succeeds.
      * @param delete data to delete if check succeeds
      * @return {@code true} if the new delete was executed, {@code false} otherwise.
      */
     boolean thenDelete(Delete delete) throws IOException;
 
     /**
+     * Specify a RowMutations to commit if the check succeeds.
      * @param mutation mutations to perform if check succeeds
      * @return true if the new mutation was executed, false otherwise.
      */
@@ -541,23 +547,27 @@ public interface Table extends Closeable {
   interface CheckAndMutateWithFilterBuilder {
 
     /**
+     * Specify a timerange.
      * @param timeRange timeRange to check
      */
     CheckAndMutateWithFilterBuilder timeRange(TimeRange timeRange);
 
     /**
+     * Specify a Put to commit if the check succeeds.
      * @param put data to put if check succeeds
      * @return {@code true} if the new put was executed, {@code false} otherwise.
      */
     boolean thenPut(Put put) throws IOException;
 
     /**
+     * Specify a Delete to commit if the check succeeds.
      * @param delete data to delete if check succeeds
      * @return {@code true} if the new delete was executed, {@code false} otherwise.
      */
     boolean thenDelete(Delete delete) throws IOException;
 
     /**
+     * Specify a RowMutations to commit if the check succeeds.
      * @param mutation mutations to perform if check succeeds
      * @return true if the new mutation was executed, false otherwise.
      */
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptor.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptor.java
index ff97f419bac..ca7590112b4 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptor.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptor.java
@@ -166,11 +166,12 @@ public interface TableDescriptor {
   String getRegionSplitPolicyClassName();
 
   /**
-   * Get the name of the table n
+   * Get the name of the table
    */
   TableName getTableName();
 
   /**
+   * Get the owner name as a string.
    * @deprecated since 2.0.0 and will be removed in 3.0.0.
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-15583">HBASE-15583</a>
    */
@@ -280,8 +281,8 @@ public interface TableDescriptor {
   boolean isReadOnly();
 
   /**
-   * @return Name of this table and then a map of all of the column family descriptors (with only
-   *         the non-default column family attributes)
+   * Returns Name of this table and then a map of all of the column family descriptors (with only
+   * the non-default column family attributes)
    */
   String toStringCustomizedValues();
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java
index 1d2b69c7146..e2dc4773d8d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java
@@ -148,8 +148,6 @@ public class TableDescriptorBuilder {
   private static final Bytes REGION_MEMSTORE_REPLICATION_KEY =
     new Bytes(Bytes.toBytes(REGION_MEMSTORE_REPLICATION));
 
-  private static final Bytes REGION_REPLICA_WAIT_FOR_PRIMARY_FLUSH_CONF_KEY =
-    new Bytes(Bytes.toBytes(RegionReplicaUtil.REGION_REPLICA_WAIT_FOR_PRIMARY_FLUSH_CONF_KEY));
   /**
    * Used by shell/rest interface to access this metadata attribute which denotes if the table
    * should be treated by region normalizer.
@@ -294,10 +292,7 @@ public class TableDescriptorBuilder {
 
   private final ModifyableTableDescriptor desc;
 
-  /**
-   * @param desc The table descriptor to serialize
-   * @return This instance serialized with pb with pb magic prefix
-   */
+  /** Returns This instance serialized with pb with pb magic prefix */
   public static byte[] toByteArray(TableDescriptor desc) {
     if (desc instanceof ModifyableTableDescriptor) {
       return ((ModifyableTableDescriptor) desc).toByteArray();
@@ -309,7 +304,7 @@ public class TableDescriptorBuilder {
    * The input should be created by {@link #toByteArray}.
    * @param pbBytes A pb serialized TableDescriptor instance with pb magic prefix
    * @return This instance serialized with pb with pb magic prefix
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException if an error occurred
    */
   public static TableDescriptor parseFrom(byte[] pbBytes) throws DeserializationException {
     return ModifyableTableDescriptor.parseFrom(pbBytes);
@@ -506,6 +501,7 @@ public class TableDescriptorBuilder {
   }
 
   /**
+   * Set the table owner
    * @deprecated since 2.0.0 and will be removed in 3.0.0.
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-15583">HBASE-15583</a>
    */
@@ -516,6 +512,7 @@ public class TableDescriptorBuilder {
   }
 
   /**
+   * Set the table owner
    * @deprecated since 2.0.0 and will be removed in 3.0.0.
    * @see <a href="https://issues.apache.org/jira/browse/HBASE-15583">HBASE-15583</a>
    */
@@ -1511,6 +1508,7 @@ public class TableDescriptorBuilder {
     }
 
     /**
+     * Set the table owner
      * @deprecated since 2.0.0 and will be removed in 3.0.0.
      * @see <a href="https://issues.apache.org/jira/browse/HBASE-15583">HBASE-15583</a>
      */
@@ -1520,6 +1518,7 @@ public class TableDescriptorBuilder {
     }
 
     /**
+     * Set the table owner.
      * @deprecated since 2.0.0 and will be removed in 3.0.0.
      * @see <a href="https://issues.apache.org/jira/browse/HBASE-15583">HBASE-15583</a>
      */
@@ -1530,6 +1529,7 @@ public class TableDescriptorBuilder {
     }
 
     /**
+     * Set the table owner.
      * @deprecated since 2.0.0 and will be removed in 3.0.0.
      * @see <a href="https://issues.apache.org/jira/browse/HBASE-15583">HBASE-15583</a>
      */
@@ -1548,6 +1548,7 @@ public class TableDescriptorBuilder {
     }
 
     /**
+     * Parse the serialized representation of a {@link ModifyableTableDescriptor}
      * @param bytes A pb serialized {@link ModifyableTableDescriptor} instance with pb magic prefix
      * @return An instance of {@link ModifyableTableDescriptor} made from <code>bytes</code> n
      *         * @see #toByteArray()
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableState.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableState.java
index 6ecd97a75c9..4e20302be45 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableState.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableState.java
@@ -209,15 +209,19 @@ public class TableState {
 
   @Override
   public boolean equals(Object o) {
-    if (this == o) return true;
-    if (o == null || getClass() != o.getClass()) return false;
-
-    TableState that = (TableState) o;
-
-    if (state != that.state) return false;
-    if (tableName != null ? !tableName.equals(that.tableName) : that.tableName != null)
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof TableState)) {
       return false;
-
+    }
+    TableState that = (TableState) o;
+    if (state != that.state) {
+      return false;
+    }
+    if (tableName != null ? !tableName.equals(that.tableName) : that.tableName != null) {
+      return false;
+    }
     return true;
   }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ClientBackoffPolicyFactory.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ClientBackoffPolicyFactory.java
index a786702b169..6993a4ac21a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ClientBackoffPolicyFactory.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ClientBackoffPolicyFactory.java
@@ -22,15 +22,11 @@ import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.util.ReflectionUtils;
 import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.yetus.audience.InterfaceStability;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 @InterfaceAudience.Private
 @InterfaceStability.Evolving
 public final class ClientBackoffPolicyFactory {
 
-  private static final Logger LOG = LoggerFactory.getLogger(ClientBackoffPolicyFactory.class);
-
   private ClientBackoffPolicyFactory() {
   }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ExponentialClientBackoffPolicy.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ExponentialClientBackoffPolicy.java
index aa84207e1ed..0e3339948ea 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ExponentialClientBackoffPolicy.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/backoff/ExponentialClientBackoffPolicy.java
@@ -21,8 +21,6 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.yetus.audience.InterfaceAudience;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
 
@@ -33,8 +31,6 @@ import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
 @InterfaceAudience.Public
 public class ExponentialClientBackoffPolicy implements ClientBackoffPolicy {
 
-  private static final Logger LOG = LoggerFactory.getLogger(ExponentialClientBackoffPolicy.class);
-
   private static final long ONE_MINUTE = 60 * 1000;
   public static final long DEFAULT_MAX_BACKOFF = 5 * ONE_MINUTE;
   public static final String MAX_BACKOFF_KEY = "hbase.client.exponential-backoff.max";
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/coprocessor/BigDecimalColumnInterpreter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/coprocessor/BigDecimalColumnInterpreter.java
index b7af4a9eff9..18592894076 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/coprocessor/BigDecimalColumnInterpreter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/coprocessor/BigDecimalColumnInterpreter.java
@@ -78,7 +78,7 @@ public class BigDecimalColumnInterpreter
 
   @Override
   public BigDecimal increment(BigDecimal bd) {
-    return bd == null ? null : (bd.add(BigDecimal.ONE));
+    return bd == null ? null : bd.add(BigDecimal.ONE);
   }
 
   @Override
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationAdmin.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationAdmin.java
index 4f94dc67a88..825eec539b1 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationAdmin.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationAdmin.java
@@ -37,8 +37,6 @@ import org.apache.hadoop.hbase.replication.ReplicationException;
 import org.apache.hadoop.hbase.replication.ReplicationPeerConfig;
 import org.apache.hadoop.hbase.replication.ReplicationPeerDescription;
 import org.apache.yetus.audience.InterfaceAudience;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import org.apache.hbase.thirdparty.com.google.common.collect.Lists;
 
@@ -65,7 +63,6 @@ import org.apache.hbase.thirdparty.com.google.common.collect.Lists;
 @InterfaceAudience.Public
 @Deprecated
 public class ReplicationAdmin implements Closeable {
-  private static final Logger LOG = LoggerFactory.getLogger(ReplicationAdmin.class);
 
   public static final String TNAME = "tableName";
   public static final String CFNAME = "columnFamilyName";
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationPeerConfigUtil.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationPeerConfigUtil.java
index 7942d9904de..c5836a99e37 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationPeerConfigUtil.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/replication/ReplicationPeerConfigUtil.java
@@ -22,6 +22,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -112,8 +113,8 @@ public final class ReplicationPeerConfigUtil {
     }
 
     ReplicationProtos.TableCF.Builder tableCFBuilder = ReplicationProtos.TableCF.newBuilder();
-    String[] tables = tableCFsConfig.split(";");
-    List<ReplicationProtos.TableCF> tableCFList = new ArrayList<>(tables.length);
+    List<String> tables = Splitter.on(';').splitToList(tableCFsConfig);
+    List<ReplicationProtos.TableCF> tableCFList = new ArrayList<>(tables.size());
 
     for (String tab : tables) {
       // 1 ignore empty table config
@@ -123,9 +124,9 @@ public final class ReplicationPeerConfigUtil {
       }
       // 2 split to "table" and "cf1,cf2"
       // for each table: "table#cf1,cf2" or "table"
-      String[] pair = tab.split(":");
-      String tabName = pair[0].trim();
-      if (pair.length > 2 || tabName.length() == 0) {
+      Iterator<String> i = Splitter.on(':').split(tab).iterator();
+      String tabName = i.next().trim();
+      if (tabName.length() == 0) {
         LOG.info("incorrect format:" + tableCFsConfig);
         continue;
       }
@@ -134,16 +135,17 @@ public final class ReplicationPeerConfigUtil {
       // split namespace from tableName
       String ns = "default";
       String tName = tabName;
-      String[] dbs = tabName.split("\\.");
-      if (dbs != null && dbs.length == 2) {
-        ns = dbs[0];
-        tName = dbs[1];
+      List<String> dbs = Splitter.on('.').splitToList(tabName);
+      if (dbs != null && dbs.size() == 2) {
+        Iterator<String> ii = dbs.iterator();
+        ns = ii.next();
+        tName = ii.next();
       }
       tableCFBuilder.setTableName(ProtobufUtil.toProtoTableName(TableName.valueOf(ns, tName)));
 
       // 3 parse "cf1,cf2" part to List<cf>
-      if (pair.length == 2) {
-        String[] cfsList = pair[1].split(",");
+      if (i.hasNext()) {
+        List<String> cfsList = Splitter.on(',').splitToList(i.next());
         for (String cf : cfsList) {
           String cfName = cf.trim();
           if (cfName.length() > 0) {
@@ -240,6 +242,7 @@ public final class ReplicationPeerConfigUtil {
   }
 
   /**
+   * Parse the serialized representation of a peer configuration.
    * @param bytes Content of a peer znode.
    * @return ClusterKey parsed from the passed bytes.
    * @throws DeserializationException deserialization exception
@@ -377,10 +380,9 @@ public final class ReplicationPeerConfigUtil {
   }
 
   /**
-   * @param peerConfig peer config of replication peer
-   * @return Serialized protobuf of <code>peerConfig</code> with pb magic prefix prepended suitable
-   *         for use as content of a this.peersZNode; i.e. the content of PEER_ID znode under
-   *         /hbase/replication/peers/PEER_ID
+   * Returns Serialized protobuf of <code>peerConfig</code> with pb magic prefix prepended suitable
+   * for use as content of a this.peersZNode; i.e. the content of PEER_ID znode under
+   * /hbase/replication/peers/PEER_ID
    */
   public static byte[] toByteArray(final ReplicationPeerConfig peerConfig) {
     byte[] bytes = convert(peerConfig).toByteArray();
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/coprocessor/ColumnInterpreter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/coprocessor/ColumnInterpreter.java
index 5ed2aba2a19..6df88561fdb 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/coprocessor/ColumnInterpreter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/coprocessor/ColumnInterpreter.java
@@ -39,11 +39,12 @@ import org.apache.yetus.audience.InterfaceStability;
  * {@link ColumnInterpreter#castToReturnType(Object)} which takes a &lt;T&gt; type and returns a
  * &lt;S&gt; type. The AggregateIm&gt;lementation uses PB messages to initialize the user's
  * ColumnInterpreter implementation, and for sending the responses back to AggregationClient.
- * @param T Cell value data type
- * @param S Promoted data type
- * @param P PB message that is used to transport initializer specific bytes
- * @param Q PB message that is used to transport Cell (&lt;T&gt;) instance
- * @param R PB message that is used to transport Promoted (&lt;S&gt;) instance
+ * <p>
+ * &lt;T&gt; Cell value data type<br>
+ * &lt;S&gt; Promoted data type<br>
+ * &lt;P&gt; PB message that is used to transport initializer specific bytes<br>
+ * &lt;Q&gt; PB message that is used to transport Cell (&lt;T&gt;) instance<br>
+ * &lt;R&gt; PB message that is used to transport Promoted (&lt;S&gt;) instance
  */
 @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
 @InterfaceStability.Evolving
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/exceptions/RegionOpeningException.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/exceptions/RegionOpeningException.java
index 347c6b987a1..bef80b2cb82 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/exceptions/RegionOpeningException.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/exceptions/RegionOpeningException.java
@@ -20,8 +20,6 @@ package org.apache.hadoop.hbase.exceptions;
 import org.apache.hadoop.hbase.NotServingRegionException;
 import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.yetus.audience.InterfaceStability;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 /**
  * Subclass if the server knows the region is now on another server. This allows the client to call
@@ -30,7 +28,7 @@ import org.slf4j.LoggerFactory;
 @InterfaceAudience.Private
 @InterfaceStability.Evolving
 public class RegionOpeningException extends NotServingRegionException {
-  private static final Logger LOG = LoggerFactory.getLogger(RegionOpeningException.class);
+
   private static final long serialVersionUID = -7232903522310558395L;
 
   public RegionOpeningException(String message) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BigDecimalComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BigDecimalComparator.java
index 669a591a961..b37bec4fc51 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BigDecimalComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BigDecimalComparator.java
@@ -82,9 +82,10 @@ public class BigDecimalComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parse a serialized representation of {@link BigDecimalComparator}
    * @param pbBytes A pb serialized {@link BigDecimalComparator} instance
    * @return An instance of {@link BigDecimalComparator} made from <code>bytes</code>
-   * @throws DeserializationException A deserialization exception
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static BigDecimalComparator parseFrom(final byte[] pbBytes)
@@ -100,10 +101,10 @@ public class BigDecimalComparator extends ByteArrayComparable {
   }
 
   /**
-   * @param other the other comparator
-   * @return true if and only if the fields of the comparator that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
+  @SuppressWarnings("ReferenceEquality")
   boolean areSerializedFieldsEqual(BigDecimalComparator other) {
     if (other == this) {
       return true;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComparator.java
index 7aff979f4c2..079cee8e642 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComparator.java
@@ -64,9 +64,11 @@ public class BinaryComparator extends org.apache.hadoop.hbase.filter.ByteArrayCo
   }
 
   /**
+   * Parse a serialized representation of {@link BinaryComparator}
    * @param pbBytes A pb serialized {@link BinaryComparator} instance
-   * @return An instance of {@link BinaryComparator} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link BinaryComparator} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static BinaryComparator parseFrom(final byte[] pbBytes) throws DeserializationException {
     ComparatorProtos.BinaryComparator proto;
@@ -79,14 +81,17 @@ public class BinaryComparator extends org.apache.hadoop.hbase.filter.ByteArrayCo
   }
 
   /**
-   * n * @return true if and only if the fields of the comparator that are serialized are equal to
-   * the corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(ByteArrayComparable other) {
-    if (other == this) return true;
-    if (!(other instanceof BinaryComparator)) return false;
-
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof BinaryComparator)) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(other);
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComponentComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComponentComparator.java
index 88622ed2eba..4d2518d23c3 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComponentComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryComponentComparator.java
@@ -84,9 +84,10 @@ public class BinaryComponentComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parse a serialized representation of {@link BinaryComponentComparator}
    * @param pbBytes A pb serialized {@link BinaryComponentComparator} instance
    * @return An instance of {@link BinaryComponentComparator} made from <code>bytes</code>
-   * @throws DeserializationException DeserializationException
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static BinaryComponentComparator parseFrom(final byte[] pbBytes)
@@ -101,9 +102,8 @@ public class BinaryComponentComparator extends ByteArrayComparable {
   }
 
   /**
-   * @param other paramemter to compare against
-   * @return true if and only if the fields of the comparator that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(ByteArrayComparable other) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryPrefixComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryPrefixComparator.java
index fcf447dcb0c..b9cbcc0826b 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryPrefixComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BinaryPrefixComparator.java
@@ -68,9 +68,11 @@ public class BinaryPrefixComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parse a serialized representation of {@link BinaryPrefixComparator}
    * @param pbBytes A pb serialized {@link BinaryPrefixComparator} instance
-   * @return An instance of {@link BinaryPrefixComparator} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link BinaryPrefixComparator} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static BinaryPrefixComparator parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -84,14 +86,17 @@ public class BinaryPrefixComparator extends ByteArrayComparable {
   }
 
   /**
-   * n * @return true if and only if the fields of the comparator that are serialized are equal to
-   * the corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(ByteArrayComparable other) {
-    if (other == this) return true;
-    if (!(other instanceof BinaryPrefixComparator)) return false;
-
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof BinaryPrefixComparator)) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(other);
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BitComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BitComparator.java
index 8abdcf4e8a6..d19738d5357 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BitComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/BitComparator.java
@@ -74,8 +74,11 @@ public class BitComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parse a serialized representation of {@link BitComparator}
    * @param pbBytes A pb serialized {@link BitComparator} instance
-   * @return An instance of {@link BitComparator} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link BitComparator} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static BitComparator parseFrom(final byte[] pbBytes) throws DeserializationException {
     ComparatorProtos.BitComparator proto;
@@ -89,14 +92,17 @@ public class BitComparator extends ByteArrayComparable {
   }
 
   /**
-   * n * @return true if and only if the fields of the comparator that are serialized are equal to
-   * the corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(ByteArrayComparable other) {
-    if (other == this) return true;
-    if (!(other instanceof BitComparator)) return false;
-
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof BitComparator)) {
+      return false;
+    }
     BitComparator comparator = (BitComparator) other;
     return super.areSerializedFieldsEqual(other)
       && this.getOperator().equals(comparator.getOperator());
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnCountGetFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnCountGetFilter.java
index a7cd0489ca5..c3bcfd80cce 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnCountGetFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnCountGetFilter.java
@@ -94,8 +94,10 @@ public class ColumnCountGetFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link ColumnCountGetFilter}
    * @param pbBytes A pb serialized {@link ColumnCountGetFilter} instance
    * @return An instance of {@link ColumnCountGetFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static ColumnCountGetFilter parseFrom(final byte[] pbBytes)
@@ -110,15 +112,17 @@ public class ColumnCountGetFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof ColumnCountGetFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof ColumnCountGetFilter)) {
+      return false;
+    }
     ColumnCountGetFilter other = (ColumnCountGetFilter) o;
     return this.getLimit() == other.getLimit();
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPaginationFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPaginationFilter.java
index e9cf7dce76d..03aa19f83c1 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPaginationFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPaginationFilter.java
@@ -78,23 +78,14 @@ public class ColumnPaginationFilter extends FilterBase {
     this.columnOffset = columnOffset;
   }
 
-  /**
-   * n
-   */
   public int getLimit() {
     return limit;
   }
 
-  /**
-   * n
-   */
   public int getOffset() {
     return offset;
   }
 
-  /**
-   * n
-   */
   public byte[] getColumnOffset() {
     return columnOffset;
   }
@@ -173,9 +164,11 @@ public class ColumnPaginationFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link ColumnPaginationFilter}
    * @param pbBytes A pb serialized {@link ColumnPaginationFilter} instance
-   * @return An instance of {@link ColumnPaginationFilter} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link ColumnPaginationFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static ColumnPaginationFilter parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -192,15 +185,17 @@ public class ColumnPaginationFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof ColumnPaginationFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof ColumnPaginationFilter)) {
+      return false;
+    }
     ColumnPaginationFilter other = (ColumnPaginationFilter) o;
     if (this.columnOffset != null) {
       return this.getLimit() == other.getLimit()
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPrefixFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPrefixFilter.java
index de76b8c5059..757b52138fc 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPrefixFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnPrefixFilter.java
@@ -117,9 +117,10 @@ public class ColumnPrefixFilter extends FilterBase {
   }
 
   /**
+   * Parses a serialized representation of the {@link ColumnPrefixFilter}
    * @param pbBytes A pb serialized {@link ColumnPrefixFilter} instance
    * @return An instance of {@link ColumnPrefixFilter} made from <code>bytes</code>
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static ColumnPrefixFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
@@ -133,15 +134,17 @@ public class ColumnPrefixFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof ColumnPrefixFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof ColumnPrefixFilter)) {
+      return false;
+    }
     ColumnPrefixFilter other = (ColumnPrefixFilter) o;
     return Bytes.equals(this.getPrefix(), other.getPrefix());
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnRangeFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnRangeFilter.java
index 1abd49fff3c..23895684682 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnRangeFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnRangeFilter.java
@@ -163,9 +163,11 @@ public class ColumnRangeFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link ColumnRangeFilter}
    * @param pbBytes A pb serialized {@link ColumnRangeFilter} instance
-   * @return An instance of {@link ColumnRangeFilter} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link ColumnRangeFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static ColumnRangeFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.ColumnRangeFilter proto;
@@ -181,9 +183,8 @@ public class ColumnRangeFilter extends FilterBase {
   }
 
   /**
-   * @param o filter to serialize.
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnValueFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnValueFilter.java
index 0b3b85dbb47..e7c06d44aef 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnValueFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ColumnValueFilter.java
@@ -168,10 +168,11 @@ public class ColumnValueFilter extends FilterBase {
   }
 
   /**
-   * Parse protobuf bytes to a ColumnValueFilter
-   * @param pbBytes pbBytes
-   * @return a ColumnValueFilter
-   * @throws DeserializationException deserialization exception
+   * Parse a serialized representation of {@link ColumnValueFilter}
+   * @param pbBytes A pb serialized {@link ColumnValueFilter} instance
+   * @return An instance of {@link ColumnValueFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static ColumnValueFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.ColumnValueFilter proto;
@@ -198,6 +199,10 @@ public class ColumnValueFilter extends FilterBase {
     return convert().toByteArray();
   }
 
+  /**
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
+   */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
     if (o == this) {
@@ -205,7 +210,6 @@ public class ColumnValueFilter extends FilterBase {
     } else if (!(o instanceof ColumnValueFilter)) {
       return false;
     }
-
     ColumnValueFilter other = (ColumnValueFilter) o;
     return Bytes.equals(this.getFamily(), other.getFamily())
       && Bytes.equals(this.getQualifier(), other.getQualifier())
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/CompareFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/CompareFilter.java
index 5b25e3b2ae1..0a54e991e30 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/CompareFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/CompareFilter.java
@@ -257,7 +257,7 @@ public abstract class CompareFilter extends FilterBase {
     }
   }
 
-  // returns an array of heterogeneous objects
+  /** Returns an array of heterogeneous objects */
   public static ArrayList<Object> extractArguments(ArrayList<byte[]> filterArguments) {
     Preconditions.checkArgument(filterArguments.size() == 2, "Expected 2 but got: %s",
       filterArguments.size());
@@ -287,13 +287,17 @@ public abstract class CompareFilter extends FilterBase {
   }
 
   /**
-   * n * @return true if and only if the fields of the filter that are serialized are equal to the
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
    * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof CompareFilter)) return false;
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof CompareFilter)) {
+      return false;
+    }
     CompareFilter other = (CompareFilter) o;
     return this.getCompareOperator().equals(other.getCompareOperator())
       && (this.getComparator() == other.getComparator()
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/DependentColumnFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/DependentColumnFilter.java
index 0a39f4c94f2..be59929dfc4 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/DependentColumnFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/DependentColumnFilter.java
@@ -230,9 +230,11 @@ public class DependentColumnFilter extends CompareFilter {
   }
 
   /**
+   * Parse a seralized representation of {@link DependentColumnFilter}
    * @param pbBytes A pb serialized {@link DependentColumnFilter} instance
-   * @return An instance of {@link DependentColumnFilter} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link DependentColumnFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static DependentColumnFilter parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -259,16 +261,19 @@ public class DependentColumnFilter extends CompareFilter {
   }
 
   /**
-   * n * @return true if and only if the fields of the filter that are serialized are equal to the
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
    * corresponding fields in other. Used for testing.
    */
   @edu.umd.cs.findbugs.annotations.SuppressWarnings(
       value = "RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE")
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof DependentColumnFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof DependentColumnFilter)) {
+      return false;
+    }
     DependentColumnFilter other = (DependentColumnFilter) o;
     return other != null && super.areSerializedFieldsEqual(other)
       && Bytes.equals(this.getFamily(), other.getFamily())
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FamilyFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FamilyFilter.java
index 917ac522de1..a5c6c8d266a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FamilyFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FamilyFilter.java
@@ -101,8 +101,11 @@ public class FamilyFilter extends CompareFilter {
   }
 
   /**
+   * Parse the serialized representation of {@link FamilyFilter}
    * @param pbBytes A pb serialized {@link FamilyFilter} instance
-   * @return An instance of {@link FamilyFilter} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link FamilyFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static FamilyFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.FamilyFilter proto;
@@ -125,14 +128,17 @@ public class FamilyFilter extends CompareFilter {
   }
 
   /**
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof FamilyFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof FamilyFilter)) {
+      return false;
+    }
     FamilyFilter other = (FamilyFilter) o;
     return super.areSerializedFieldsEqual(other);
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/Filter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/Filter.java
index 9df8a6f14f3..cac538dcb8a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/Filter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/Filter.java
@@ -241,7 +241,9 @@ public abstract class Filter {
    * Concrete implementers can signal a failure condition in their code by throwing an
    * {@link IOException}.
    * @param pbBytes A pb serialized {@link Filter} instance
-   * @return An instance of {@link Filter} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link Filter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static Filter parseFrom(final byte[] pbBytes) throws DeserializationException {
     throw new DeserializationException(
@@ -252,7 +254,6 @@ public abstract class Filter {
    * Concrete implementers can signal a failure condition in their code by throwing an
    * {@link IOException}. n * @return true if and only if the fields of the filter that are
    * serialized are equal to the corresponding fields in other. Used for testing.
-   * @throws IOException in case an I/O or an filter specific failure needs to be signaled.
    */
   abstract boolean areSerializedFieldsEqual(Filter other);
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterList.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterList.java
index 35313837843..1e00f08757f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterList.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterList.java
@@ -205,8 +205,11 @@ final public class FilterList extends FilterBase {
   }
 
   /**
+   * Parse a seralized representation of {@link FilterList}
    * @param pbBytes A pb serialized {@link FilterList} instance
-   * @return An instance of {@link FilterList} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link FilterList} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static FilterList parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.FilterList proto;
@@ -229,14 +232,17 @@ final public class FilterList extends FilterBase {
   }
 
   /**
-   * n * @return true if and only if the fields of the filter that are serialized are equal to the
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
    * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter other) {
-    if (other == this) return true;
-    if (!(other instanceof FilterList)) return false;
-
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof FilterList)) {
+      return false;
+    }
     FilterList o = (FilterList) other;
     return this.getOperator().equals(o.getOperator())
       && ((this.getFilters() == o.getFilters()) || this.getFilters().equals(o.getFilters()));
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithAND.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithAND.java
index 6ea8e14257c..7347ca3357d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithAND.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithAND.java
@@ -285,12 +285,12 @@ public class FilterListWithAND extends FilterListBase {
 
   @Override
   public boolean equals(Object obj) {
-    if (!(obj instanceof FilterListWithAND)) {
-      return false;
-    }
     if (this == obj) {
       return true;
     }
+    if (!(obj instanceof FilterListWithAND)) {
+      return false;
+    }
     FilterListWithAND f = (FilterListWithAND) obj;
     return this.filters.equals(f.getFilters()) && this.seekHintFilters.equals(f.seekHintFilters);
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithOR.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithOR.java
index 690b32babba..5bc1a151e83 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithOR.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FilterListWithOR.java
@@ -409,12 +409,12 @@ public class FilterListWithOR extends FilterListBase {
 
   @Override
   public boolean equals(Object obj) {
-    if (obj == null || (!(obj instanceof FilterListWithOR))) {
-      return false;
-    }
     if (this == obj) {
       return true;
     }
+    if (!(obj instanceof FilterListWithOR)) {
+      return false;
+    }
     FilterListWithOR f = (FilterListWithOR) obj;
     return this.filters.equals(f.getFilters()) && this.prevFilterRCList.equals(f.prevFilterRCList)
       && this.prevCellList.equals(f.prevCellList);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyOnlyFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyOnlyFilter.java
index d779d36eef7..1b9f277814b 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyOnlyFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyOnlyFilter.java
@@ -19,7 +19,6 @@ package org.apache.hadoop.hbase.filter;
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Objects;
 import org.apache.hadoop.hbase.Cell;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
 import org.apache.yetus.audience.InterfaceAudience;
@@ -77,6 +76,7 @@ public class FirstKeyOnlyFilter extends FilterBase {
   }
 
   /**
+   * Set or clear the indication if the first KV has been found.
    * @param value update {@link #foundKV} flag with value.
    */
   protected void setFoundKV(boolean value) {
@@ -91,9 +91,10 @@ public class FirstKeyOnlyFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link FirstKeyOnlyFilter}
    * @param pbBytes A pb serialized {@link FirstKeyOnlyFilter} instance
    * @return An instance of {@link FirstKeyOnlyFilter} made from <code>bytes</code>
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static FirstKeyOnlyFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
@@ -108,15 +109,17 @@ public class FirstKeyOnlyFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof FirstKeyOnlyFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof FirstKeyOnlyFilter)) {
+      return false;
+    }
     return true;
   }
 
@@ -127,6 +130,6 @@ public class FirstKeyOnlyFilter extends FilterBase {
 
   @Override
   public int hashCode() {
-    return Objects.hashCode(foundKV);
+    return Boolean.hashCode(foundKV);
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyValueMatchingQualifiersFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyValueMatchingQualifiersFilter.java
index b49e51f348c..95f35c6f674 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyValueMatchingQualifiersFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyValueMatchingQualifiersFilter.java
@@ -95,9 +95,12 @@ public class FirstKeyValueMatchingQualifiersFilter extends FirstKeyOnlyFilter {
   }
 
   /**
+   * Parses a serialized representation of {@link FirstKeyValueMatchingQualifiersFilter}
    * @param pbBytes A pb serialized {@link FirstKeyValueMatchingQualifiersFilter} instance
    * @return An instance of {@link FirstKeyValueMatchingQualifiersFilter} made from
-   *         <code>bytes</code> n * @see #toByteArray
+   *         <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static FirstKeyValueMatchingQualifiersFilter parseFrom(final byte[] pbBytes)
     throws DeserializationException {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FuzzyRowFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FuzzyRowFilter.java
index 6036aebdd57..36c1fe2cffa 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FuzzyRowFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FuzzyRowFilter.java
@@ -299,9 +299,11 @@ public class FuzzyRowFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link FuzzyRowFilter}
    * @param pbBytes A pb serialized {@link FuzzyRowFilter} instance
-   * @return An instance of {@link FuzzyRowFilter} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link FuzzyRowFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static FuzzyRowFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.FuzzyRowFilter proto;
@@ -379,7 +381,7 @@ public class FuzzyRowFilter extends FilterBase {
       long fuzzyBytes = Bytes.toLong(fuzzyKeyBytes, i);
       long fuzzyMeta = Bytes.toLong(fuzzyKeyMeta, i);
       long rowValue = Bytes.toLong(row, offset + i);
-      if ((rowValue & fuzzyMeta) != (fuzzyBytes)) {
+      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
         // We always return NEXT_EXISTS
         return SatisfiesCode.NEXT_EXISTS;
       }
@@ -391,7 +393,7 @@ public class FuzzyRowFilter extends FilterBase {
       int fuzzyBytes = Bytes.toInt(fuzzyKeyBytes, off);
       int fuzzyMeta = Bytes.toInt(fuzzyKeyMeta, off);
       int rowValue = Bytes.toInt(row, offset + off);
-      if ((rowValue & fuzzyMeta) != (fuzzyBytes)) {
+      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
         // We always return NEXT_EXISTS
         return SatisfiesCode.NEXT_EXISTS;
       }
@@ -402,7 +404,7 @@ public class FuzzyRowFilter extends FilterBase {
       short fuzzyBytes = Bytes.toShort(fuzzyKeyBytes, off);
       short fuzzyMeta = Bytes.toShort(fuzzyKeyMeta, off);
       short rowValue = Bytes.toShort(row, offset + off);
-      if ((rowValue & fuzzyMeta) != (fuzzyBytes)) {
+      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
         // We always return NEXT_EXISTS
         // even if it does not (in this case getNextForFuzzyRule
         // will return null)
@@ -415,7 +417,7 @@ public class FuzzyRowFilter extends FilterBase {
       int fuzzyBytes = fuzzyKeyBytes[off] & 0xff;
       int fuzzyMeta = fuzzyKeyMeta[off] & 0xff;
       int rowValue = row[offset + off] & 0xff;
-      if ((rowValue & fuzzyMeta) != (fuzzyBytes)) {
+      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
         // We always return NEXT_EXISTS
         return SatisfiesCode.NEXT_EXISTS;
       }
@@ -645,14 +647,17 @@ public class FuzzyRowFilter extends FilterBase {
   }
 
   /**
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof FuzzyRowFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof FuzzyRowFilter)) {
+      return false;
+    }
     FuzzyRowFilter other = (FuzzyRowFilter) o;
     if (this.fuzzyKeysData.size() != other.fuzzyKeysData.size()) return false;
     for (int i = 0; i < fuzzyKeysData.size(); ++i) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/InclusiveStopFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/InclusiveStopFilter.java
index 67a214e5650..43204211bfb 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/InclusiveStopFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/InclusiveStopFilter.java
@@ -92,9 +92,11 @@ public class InclusiveStopFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link InclusiveStopFilter}
    * @param pbBytes A pb serialized {@link InclusiveStopFilter} instance
-   * @return An instance of {@link InclusiveStopFilter} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link InclusiveStopFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static InclusiveStopFilter parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -109,15 +111,17 @@ public class InclusiveStopFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof InclusiveStopFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof InclusiveStopFilter)) {
+      return false;
+    }
     InclusiveStopFilter other = (InclusiveStopFilter) o;
     return Bytes.equals(this.getStopRowKey(), other.getStopRowKey());
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/KeyOnlyFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/KeyOnlyFilter.java
index 60b3a5c0480..ff17b0c681d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/KeyOnlyFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/KeyOnlyFilter.java
@@ -108,8 +108,11 @@ public class KeyOnlyFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link KeyOnlyFilter}
    * @param pbBytes A pb serialized {@link KeyOnlyFilter} instance
-   * @return An instance of {@link KeyOnlyFilter} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link KeyOnlyFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static KeyOnlyFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.KeyOnlyFilter proto;
@@ -122,15 +125,17 @@ public class KeyOnlyFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof KeyOnlyFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof KeyOnlyFilter)) {
+      return false;
+    }
     KeyOnlyFilter other = (KeyOnlyFilter) o;
     return this.lenAsVal == other.lenAsVal;
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/LongComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/LongComparator.java
index 8f9a7f1dfc3..c71afa098fe 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/LongComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/LongComparator.java
@@ -62,9 +62,10 @@ public class LongComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parses a serialized representation of {@link LongComparator}
    * @param pbBytes A pb serialized {@link LongComparator} instance
    * @return An instance of {@link LongComparator} made from <code>bytes</code>
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static LongComparator parseFrom(final byte[] pbBytes) throws DeserializationException {
@@ -78,11 +79,16 @@ public class LongComparator extends ByteArrayComparable {
   }
 
   /**
-   * n * @return true if and only if the fields of the comparator that are serialized are equal to
-   * the corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   boolean areSerializedFieldsEqual(LongComparator other) {
-    if (other == this) return true;
+    if (other == this) {
+      return true;
+    }
+    if (other == null) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(other);
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultiRowRangeFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultiRowRangeFilter.java
index af07cc42b11..cc9abbc2293 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultiRowRangeFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultiRowRangeFilter.java
@@ -203,9 +203,11 @@ public class MultiRowRangeFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link MultiRowRangeFilter}
    * @param pbBytes A pb serialized instance
-   * @return An instance of MultiRowRangeFilter
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @return An instance of {@link MultiRowRangeFilter}
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static MultiRowRangeFilter parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -230,15 +232,17 @@ public class MultiRowRangeFilter extends FilterBase {
   }
 
   /**
-   * @param o the filter to compare
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof MultiRowRangeFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof MultiRowRangeFilter)) {
+      return false;
+    }
     MultiRowRangeFilter other = (MultiRowRangeFilter) o;
     if (this.rangeList.size() != other.rangeList.size()) return false;
     for (int i = 0; i < rangeList.size(); ++i) {
@@ -725,7 +729,7 @@ public class MultiRowRangeFilter extends FilterBase {
     /**
      * Gets the RowRange at the given offset.
      */
-    @SuppressWarnings("unchecked")
+    @SuppressWarnings({ "unchecked", "TypeParameterUnusedInFormals" })
     public <T extends BasicRowRange> T get(int i) {
       return (T) ranges.get(i);
     }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultipleColumnPrefixFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultipleColumnPrefixFilter.java
index e7c868e3bbb..ed061a5756f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultipleColumnPrefixFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultipleColumnPrefixFilter.java
@@ -134,9 +134,11 @@ public class MultipleColumnPrefixFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link MultipleColumnPrefixFilter}
    * @param pbBytes A pb serialized {@link MultipleColumnPrefixFilter} instance
-   * @return An instance of {@link MultipleColumnPrefixFilter} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link MultipleColumnPrefixFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static MultipleColumnPrefixFilter parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -156,15 +158,17 @@ public class MultipleColumnPrefixFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof MultipleColumnPrefixFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof MultipleColumnPrefixFilter)) {
+      return false;
+    }
     MultipleColumnPrefixFilter other = (MultipleColumnPrefixFilter) o;
     return this.sortedPrefixes.equals(other.sortedPrefixes);
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/NullComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/NullComparator.java
index 6153e1e8080..ea8a5abd354 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/NullComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/NullComparator.java
@@ -71,9 +71,11 @@ public class NullComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parse the serialized representation of {@link NullComparator}
    * @param pbBytes A pb serialized {@link NullComparator} instance
-   * @return An instance of {@link NullComparator} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link NullComparator} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static NullComparator parseFrom(final byte[] pbBytes) throws DeserializationException {
     try {
@@ -86,14 +88,17 @@ public class NullComparator extends ByteArrayComparable {
   }
 
   /**
-   * n * @return true if and only if the fields of the comparator that are serialized are equal to
-   * the corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(ByteArrayComparable other) {
-    if (other == this) return true;
-    if (!(other instanceof NullComparator)) return false;
-
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof NullComparator)) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(other);
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PageFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PageFilter.java
index 45c8a1f1a3f..dd6f4eca405 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PageFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PageFilter.java
@@ -106,8 +106,11 @@ public class PageFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link PageFilter}
    * @param pbBytes A pb serialized {@link PageFilter} instance
-   * @return An instance of {@link PageFilter} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link PageFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static PageFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.PageFilter proto;
@@ -120,9 +123,8 @@ public class PageFilter extends FilterBase {
   }
 
   /**
-   * @param o other Filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ParseFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ParseFilter.java
index c9ebace2da2..b4f24ef97d0 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ParseFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ParseFilter.java
@@ -157,7 +157,7 @@ public class ParseFilter {
           operatorStack.pop();
           continue;
         }
-        while (!(argumentOnTopOfStack.equals(ParseConstants.LPAREN_BUFFER))) {
+        while (!argumentOnTopOfStack.equals(ParseConstants.LPAREN_BUFFER)) {
           filterStack.push(popArguments(operatorStack, filterStack));
           if (operatorStack.empty()) {
             throw new IllegalArgumentException("Mismatched parenthesis");
@@ -242,17 +242,12 @@ public class ParseFilter {
       Class<?>[] argTypes = new Class[] { ArrayList.class };
       Method m = c.getDeclaredMethod("createFilterFromArguments", argTypes);
       return (Filter) m.invoke(null, filterArguments);
-    } catch (ClassNotFoundException e) {
-      e.printStackTrace();
-    } catch (NoSuchMethodException e) {
-      e.printStackTrace();
-    } catch (IllegalAccessException e) {
-      e.printStackTrace();
-    } catch (InvocationTargetException e) {
-      e.printStackTrace();
+    } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException
+      | InvocationTargetException e) {
+      LOG.warn("Exception while invoking createFilterFromArguments", e);
+      throw new IllegalArgumentException(
+        "Incorrect filter string " + new String(filterStringAsByteArray, StandardCharsets.UTF_8));
     }
-    throw new IllegalArgumentException(
-      "Incorrect filter string " + new String(filterStringAsByteArray, StandardCharsets.UTF_8));
   }
 
   /**
@@ -367,7 +362,7 @@ public class ParseFilter {
   public void reduce(Stack<ByteBuffer> operatorStack, Stack<Filter> filterStack,
     ByteBuffer operator) {
     while (
-      !operatorStack.empty() && !(ParseConstants.LPAREN_BUFFER.equals(operatorStack.peek()))
+      !operatorStack.empty() && !ParseConstants.LPAREN_BUFFER.equals(operatorStack.peek())
         && hasHigherPriority(operatorStack.peek(), operator)
     ) {
       filterStack.push(popArguments(operatorStack, filterStack));
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PrefixFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PrefixFilter.java
index 51752d2b72f..711b6d59944 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PrefixFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PrefixFilter.java
@@ -116,9 +116,10 @@ public class PrefixFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link PrefixFilter}
    * @param pbBytes A pb serialized {@link PrefixFilter} instance
    * @return An instance of {@link PrefixFilter} made from <code>bytes</code>
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static PrefixFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
@@ -132,15 +133,17 @@ public class PrefixFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof PrefixFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof PrefixFilter)) {
+      return false;
+    }
     PrefixFilter other = (PrefixFilter) o;
     return Bytes.equals(this.getPrefix(), other.getPrefix());
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/QualifierFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/QualifierFilter.java
index 7f0b8642003..328c7fd57c6 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/QualifierFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/QualifierFilter.java
@@ -95,9 +95,10 @@ public class QualifierFilter extends CompareFilter {
   }
 
   /**
+   * Parse a serialized representation of {@link QualifierFilter}
    * @param pbBytes A pb serialized {@link QualifierFilter} instance
    * @return An instance of {@link QualifierFilter} made from <code>bytes</code>
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static QualifierFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
@@ -121,14 +122,17 @@ public class QualifierFilter extends CompareFilter {
   }
 
   /**
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof QualifierFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof QualifierFilter)) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(o);
   }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RandomRowFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RandomRowFilter.java
index 656ceaf3e1a..f7e0281b112 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RandomRowFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RandomRowFilter.java
@@ -114,9 +114,11 @@ public class RandomRowFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link RandomRowFilter}
    * @param pbBytes A pb serialized {@link RandomRowFilter} instance
-   * @return An instance of {@link RandomRowFilter} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link RandomRowFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static RandomRowFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.RandomRowFilter proto;
@@ -129,15 +131,17 @@ public class RandomRowFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof RandomRowFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof RandomRowFilter)) {
+      return false;
+    }
     RandomRowFilter other = (RandomRowFilter) o;
     return this.getChance() == other.getChance();
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RegexStringComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RegexStringComparator.java
index 4bdc057bd9e..9efa563b432 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RegexStringComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RegexStringComparator.java
@@ -152,9 +152,11 @@ public class RegexStringComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parse a serialized representation of {@link RegexStringComparator}
    * @param pbBytes A pb serialized {@link RegexStringComparator} instance
-   * @return An instance of {@link RegexStringComparator} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link RegexStringComparator} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static RegexStringComparator parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -183,13 +185,17 @@ public class RegexStringComparator extends ByteArrayComparable {
   }
 
   /**
-   * n * @return true if and only if the fields of the comparator that are serialized are equal to
-   * the corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(ByteArrayComparable other) {
-    if (other == this) return true;
-    if (!(other instanceof RegexStringComparator)) return false;
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof RegexStringComparator)) {
+      return false;
+    }
     RegexStringComparator comparator = (RegexStringComparator) other;
     return super.areSerializedFieldsEqual(comparator)
       && engine.getClass().isInstance(comparator.getEngine())
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RowFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RowFilter.java
index fdefe382439..cdebf0a15dc 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RowFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/RowFilter.java
@@ -115,8 +115,11 @@ public class RowFilter extends CompareFilter {
   }
 
   /**
+   * Parse a serialized representation of {@link RowFilter}
    * @param pbBytes A pb serialized {@link RowFilter} instance
-   * @return An instance of {@link RowFilter} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link RowFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static RowFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.RowFilter proto;
@@ -139,14 +142,17 @@ public class RowFilter extends CompareFilter {
   }
 
   /**
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof RowFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof RowFilter)) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(o);
   }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueExcludeFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueExcludeFilter.java
index bbd8ec67994..d3f65efac4a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueExcludeFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueExcludeFilter.java
@@ -173,9 +173,11 @@ public class SingleColumnValueExcludeFilter extends SingleColumnValueFilter {
   }
 
   /**
+   * Parse a serialized representation of {@link SingleColumnValueExcludeFilter}
    * @param pbBytes A pb serialized {@link SingleColumnValueExcludeFilter} instance
-   * @return An instance of {@link SingleColumnValueExcludeFilter} made from <code>bytes</code> n
-   *         * @see #toByteArray
+   * @return An instance of {@link SingleColumnValueExcludeFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static SingleColumnValueExcludeFilter parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -202,14 +204,17 @@ public class SingleColumnValueExcludeFilter extends SingleColumnValueFilter {
   }
 
   /**
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof SingleColumnValueExcludeFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof SingleColumnValueExcludeFilter)) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(o);
   }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueFilter.java
index a68fdcd0577..7048563d0d6 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SingleColumnValueFilter.java
@@ -357,8 +357,10 @@ public class SingleColumnValueFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link SingleColumnValueFilter}
    * @param pbBytes A pb serialized {@link SingleColumnValueFilter} instance
    * @return An instance of {@link SingleColumnValueFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static SingleColumnValueFilter parseFrom(final byte[] pbBytes)
@@ -385,8 +387,8 @@ public class SingleColumnValueFilter extends FilterBase {
   }
 
   /**
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SkipFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SkipFilter.java
index 4b23a87537d..1fca852d558 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SkipFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SkipFilter.java
@@ -111,8 +111,11 @@ public class SkipFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link SkipFilter}
    * @param pbBytes A pb serialized {@link SkipFilter} instance
-   * @return An instance of {@link SkipFilter} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link SkipFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static SkipFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.SkipFilter proto;
@@ -129,15 +132,17 @@ public class SkipFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof SkipFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof SkipFilter)) {
+      return false;
+    }
     SkipFilter other = (SkipFilter) o;
     return getFilter().areSerializedFieldsEqual(other.getFilter());
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SubstringComparator.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SubstringComparator.java
index b5fe22dca24..8312d3f673f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SubstringComparator.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/SubstringComparator.java
@@ -76,9 +76,11 @@ public class SubstringComparator extends ByteArrayComparable {
   }
 
   /**
+   * Parse a serialized representation of {@link SubstringComparator}
    * @param pbBytes A pb serialized {@link SubstringComparator} instance
-   * @return An instance of {@link SubstringComparator} made from <code>bytes</code> n * @see
-   *         #toByteArray
+   * @return An instance of {@link SubstringComparator} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static SubstringComparator parseFrom(final byte[] pbBytes)
     throws DeserializationException {
@@ -92,14 +94,17 @@ public class SubstringComparator extends ByteArrayComparable {
   }
 
   /**
-   * n * @return true if and only if the fields of the comparator that are serialized are equal to
-   * the corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the comparator that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(ByteArrayComparable other) {
-    if (other == this) return true;
-    if (!(other instanceof SubstringComparator)) return false;
-
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof SubstringComparator)) {
+      return false;
+    }
     SubstringComparator comparator = (SubstringComparator) other;
     return super.areSerializedFieldsEqual(comparator) && this.substr.equals(comparator.substr);
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/TimestampsFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/TimestampsFilter.java
index eaeaaac3df1..5b3153649e0 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/TimestampsFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/TimestampsFilter.java
@@ -173,8 +173,10 @@ public class TimestampsFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link TimestampsFilter}
    * @param pbBytes A pb serialized {@link TimestampsFilter} instance
    * @return An instance of {@link TimestampsFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static TimestampsFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
@@ -189,15 +191,17 @@ public class TimestampsFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof TimestampsFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof TimestampsFilter)) {
+      return false;
+    }
     TimestampsFilter other = (TimestampsFilter) o;
     return this.getTimestamps().equals(other.getTimestamps());
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ValueFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ValueFilter.java
index e726d88f720..5339530923f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ValueFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/ValueFilter.java
@@ -96,8 +96,11 @@ public class ValueFilter extends CompareFilter {
   }
 
   /**
+   * Parse a serialized representation of {@link ValueFilter}
    * @param pbBytes A pb serialized {@link ValueFilter} instance
-   * @return An instance of {@link ValueFilter} made from <code>bytes</code> n * @see #toByteArray
+   * @return An instance of {@link ValueFilter} made from <code>bytes</code>
+   * @throws DeserializationException if an error occurred
+   * @see #toByteArray
    */
   public static ValueFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
     FilterProtos.ValueFilter proto;
@@ -120,14 +123,17 @@ public class ValueFilter extends CompareFilter {
   }
 
   /**
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Returns true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof ValueFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof ValueFilter)) {
+      return false;
+    }
     return super.areSerializedFieldsEqual(o);
   }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/WhileMatchFilter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/WhileMatchFilter.java
index e31cbb97378..61433e4b509 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/WhileMatchFilter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/WhileMatchFilter.java
@@ -116,9 +116,10 @@ public class WhileMatchFilter extends FilterBase {
   }
 
   /**
+   * Parse a serialized representation of {@link WhileMatchFilter}
    * @param pbBytes A pb serialized {@link WhileMatchFilter} instance
    * @return An instance of {@link WhileMatchFilter} made from <code>bytes</code>
-   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
+   * @throws DeserializationException if an error occurred
    * @see #toByteArray
    */
   public static WhileMatchFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
@@ -136,15 +137,17 @@ public class WhileMatchFilter extends FilterBase {
   }
 
   /**
-   * @param o the other filter to compare with
-   * @return true if and only if the fields of the filter that are serialized are equal to the
-   *         corresponding fields in other. Used for testing.
+   * Return true if and only if the fields of the filter that are serialized are equal to the
+   * corresponding fields in other. Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
-    if (o == this) return true;
-    if (!(o instanceof WhileMatchFilter)) return false;
-
+    if (o == this) {
+      return true;
+    }
+    if (!(o instanceof WhileMatchFilter)) {
+      return false;
+    }
     WhileMatchFilter other = (WhileMatchFilter) o;
     return getFilter().areSerializedFieldsEqual(other.getFilter());
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/package-info.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/package-info.java
index 9dea2548ea9..e4d3ab947da 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/package-info.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/filter/package-info.java
@@ -20,15 +20,14 @@
 /**
  * Provides row-level filters applied to HRegion scan results during calls to
  * {@link org.apache.hadoop.hbase.client.ResultScanner#next()}.
-
-<p>
-Filters run the extent of a table unless you wrap your filter in a
-{@link org.apache.hadoop.hbase.filter.WhileMatchFilter}.
-The latter returns as soon as the filter stops matching.
-</p>
-<p>Do not rely on filters carrying state across rows; its not reliable in current
-hbase as we have no handlers in place for when regions split, close or server
-crashes.
-</p>
-*/
+ *
+ * <p>
+ * Filters run the extent of a table unless you wrap your filter in a
+ * {@link org.apache.hadoop.hbase.filter.WhileMatchFilter}.
+ * The latter returns as soon as the filter stops matching.
+ * </p>
+ * <p>Do not rely on filters carrying state across rows; its not reliable in current
+ * hbase as we have no handlers in place for when regions split, close or server
+ * crashes.
+ */
 package org.apache.hadoop.hbase.filter;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/AbstractRpcClient.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/AbstractRpcClient.java
index 7c0149ccb8a..9d557a98743 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/AbstractRpcClient.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/AbstractRpcClient.java
@@ -238,7 +238,8 @@ public abstract class AbstractRpcClient<T extends RpcConnection> implements RpcC
       return null;
     }
     try {
-      return (Codec) Class.forName(className).getDeclaredConstructor().newInstance();
+      return Class.forName(className).asSubclass(Codec.class).getDeclaredConstructor()
+        .newInstance();
     } catch (Exception e) {
       throw new RuntimeException("Failed getting codec " + className, e);
     }
@@ -265,7 +266,8 @@ public abstract class AbstractRpcClient<T extends RpcConnection> implements RpcC
       return null;
     }
     try {
-      return (CompressionCodec) Class.forName(className).getDeclaredConstructor().newInstance();
+      return Class.forName(className).asSubclass(CompressionCodec.class).getDeclaredConstructor()
+        .newInstance();
     } catch (Exception e) {
       throw new RuntimeException("Failed getting compressor " + className, e);
     }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BlockingRpcConnection.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BlockingRpcConnection.java
index c8adc6a8cc3..da032cbeb9d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BlockingRpcConnection.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BlockingRpcConnection.java
@@ -67,7 +67,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import org.apache.hbase.thirdparty.com.google.protobuf.Message;
-import org.apache.hbase.thirdparty.com.google.protobuf.Message.Builder;
 import org.apache.hbase.thirdparty.com.google.protobuf.RpcCallback;
 import org.apache.hbase.thirdparty.io.netty.buffer.ByteBuf;
 import org.apache.hbase.thirdparty.io.netty.buffer.PooledByteBufAllocator;
@@ -181,6 +180,8 @@ class BlockingRpcConnection extends RpcConnection implements Runnable {
             try {
               BlockingRpcConnection.this.wait();
             } catch (InterruptedException e) {
+              // Restore interrupt status
+              Thread.currentThread().interrupt();
             }
             // check if we need to quit, so continue the main loop instead of fallback.
             continue;
@@ -333,6 +334,8 @@ class BlockingRpcConnection extends RpcConnection implements Runnable {
       try {
         wait(Math.min(this.rpcClient.minIdleTimeBeforeClose, 1000));
       } catch (InterruptedException e) {
+        // Restore interrupt status
+        Thread.currentThread().interrupt();
       }
     }
   }
@@ -685,7 +688,7 @@ class BlockingRpcConnection extends RpcConnection implements Runnable {
       } else {
         Message value = null;
         if (call.responseDefaultType != null) {
-          Builder builder = call.responseDefaultType.newBuilderForType();
+          Message.Builder builder = call.responseDefaultType.newBuilderForType();
           ProtobufUtil.mergeDelimitedFrom(builder, in);
           value = builder.build();
         }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BufferCallBeforeInitHandler.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BufferCallBeforeInitHandler.java
index 3dc48ce3e00..53ac3d86fe5 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BufferCallBeforeInitHandler.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BufferCallBeforeInitHandler.java
@@ -20,6 +20,7 @@ package org.apache.hadoop.hbase.ipc;
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
+import org.apache.hadoop.hbase.util.NettyFutureUtils;
 import org.apache.yetus.audience.InterfaceAudience;
 
 import org.apache.hbase.thirdparty.io.netty.channel.ChannelDuplexHandler;
@@ -73,7 +74,7 @@ class BufferCallBeforeInitHandler extends ChannelDuplexHandler {
       // We will fail the call directly if we can not write it out.
       promise.trySuccess();
     } else {
-      ctx.write(msg, promise);
+      NettyFutureUtils.consume(ctx.write(msg, promise));
     }
   }
 
@@ -84,7 +85,7 @@ class BufferCallBeforeInitHandler extends ChannelDuplexHandler {
       switch (bcEvt.action) {
         case FLUSH:
           for (Call call : id2Call.values()) {
-            ctx.write(call);
+            NettyFutureUtils.safeWrite(ctx, call);
           }
           break;
         case FAIL:
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/CellBlockBuilder.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/CellBlockBuilder.java
index 9e9c0688ece..b2b3698aa2c 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/CellBlockBuilder.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/CellBlockBuilder.java
@@ -228,6 +228,7 @@ class CellBlockBuilder {
   }
 
   /**
+   * Create a cell scanner.
    * @param codec     to use for cellblock
    * @param cellBlock to encode
    * @return CellScanner to work against the content of <code>cellBlock</code>
@@ -248,6 +249,7 @@ class CellBlockBuilder {
   }
 
   /**
+   * Create a cell scanner using an existing bytebuff.
    * @param codec     to use for cellblock
    * @param cellBlock ByteBuffer containing the cells written by the Codec. The buffer should be
    *                  position()'ed at the start of the cell block and limit()'ed at the end.
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/ConnectionId.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/ConnectionId.java
index 6cb9cddd9fe..4de82e0c12a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/ConnectionId.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/ConnectionId.java
@@ -57,14 +57,18 @@ class ConnectionId {
   }
 
   @Override
+  @SuppressWarnings("ReferenceEquality")
   public boolean equals(Object obj) {
-    if (obj instanceof ConnectionId) {
-      ConnectionId id = (ConnectionId) obj;
-      return address.equals(id.address)
-        && ((ticket != null && ticket.equals(id.ticket)) || (ticket == id.ticket))
-        && Objects.equals(this.serviceName, id.serviceName);
+    if (obj == this) {
+      return true;
     }
-    return false;
+    if (!(obj instanceof ConnectionId)) {
+      return false;
+    }
+    ConnectionId id = (ConnectionId) obj;
+    return address.equals(id.address)
+      && ((ticket != null && ticket.equals(id.ticket)) || (ticket == id.ticket))
+      && Objects.equals(this.serviceName, id.serviceName);
   }
 
   @Override // simply use the default Object#hashcode() ?
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/HBaseRpcController.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/HBaseRpcController.java
index 01412631ef7..c60de7658f3 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/HBaseRpcController.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/HBaseRpcController.java
@@ -50,12 +50,14 @@ public interface HBaseRpcController extends RpcController, CellScannable {
   void setCellScanner(CellScanner cellScanner);
 
   /**
+   * Set the priority for this operation.
    * @param priority Priority for this request; should fall roughly in the range
    *                 {@link HConstants#NORMAL_QOS} to {@link HConstants#HIGH_QOS}
    */
   void setPriority(int priority);
 
   /**
+   * Set the priority for this operation.
    * @param tn Set priority based off the table we are going against.
    */
   void setPriority(final TableName tn);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcClient.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcClient.java
index 7b698958ede..22123eb2a60 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcClient.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcClient.java
@@ -23,6 +23,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HBaseInterfaceAudience;
 import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.client.MetricsConnection;
+import org.apache.hadoop.hbase.util.NettyFutureUtils;
 import org.apache.hadoop.hbase.util.Pair;
 import org.apache.yetus.audience.InterfaceAudience;
 
@@ -78,7 +79,7 @@ public class NettyRpcClient extends AbstractRpcClient<NettyRpcConnection> {
   @Override
   protected void closeInternal() {
     if (shutdownGroupWhenClose) {
-      group.shutdownGracefully();
+      NettyFutureUtils.consume(group.shutdownGracefully());
     }
   }
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcConnection.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcConnection.java
index d211b1b98e5..2e6bd1025af 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcConnection.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcConnection.java
@@ -35,6 +35,7 @@ import org.apache.hadoop.hbase.ipc.HBaseRpcController.CancellationCallback;
 import org.apache.hadoop.hbase.security.NettyHBaseRpcConnectionHeaderHandler;
 import org.apache.hadoop.hbase.security.NettyHBaseSaslRpcClientHandler;
 import org.apache.hadoop.hbase.security.SaslChallengeDecoder;
+import org.apache.hadoop.hbase.util.NettyFutureUtils;
 import org.apache.hadoop.hbase.util.Threads;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.yetus.audience.InterfaceAudience;
@@ -129,7 +130,7 @@ class NettyRpcConnection extends RpcConnection {
   private void shutdown0() {
     assert eventLoop.inEventLoop();
     if (channel != null) {
-      channel.close();
+      NettyFutureUtils.consume(channel.close());
       channel = null;
     }
   }
@@ -167,6 +168,7 @@ class NettyRpcConnection extends RpcConnection {
 
   private boolean reloginInProgress;
 
+  @SuppressWarnings("FutureReturnValueIgnored")
   private void scheduleRelogin(Throwable error) {
     assert eventLoop.inEventLoop();
     if (error instanceof FallbackDisallowedException) {
@@ -217,7 +219,7 @@ class NettyRpcConnection extends RpcConnection {
       return;
     }
     ch.pipeline().addFirst(new SaslChallengeDecoder(), saslHandler);
-    saslPromise.addListener(new FutureListener<Boolean>() {
+    NettyFutureUtils.consume(saslPromise.addListener(new FutureListener<Boolean>() {
 
       @Override
       public void operationComplete(Future<Boolean> future) throws Exception {
@@ -235,26 +237,27 @@ class NettyRpcConnection extends RpcConnection {
             p.addFirst(
               new ReadTimeoutHandler(RpcClient.DEFAULT_SOCKET_TIMEOUT_READ, TimeUnit.MILLISECONDS));
             p.addLast(chHandler);
-            connectionHeaderPromise.addListener(new FutureListener<Boolean>() {
-              @Override
-              public void operationComplete(Future<Boolean> future) throws Exception {
-                if (future.isSuccess()) {
-                  ChannelPipeline p = ch.pipeline();
-                  p.remove(ReadTimeoutHandler.class);
-                  p.remove(NettyHBaseRpcConnectionHeaderHandler.class);
-                  // don't send connection header, NettyHbaseRpcConnectionHeaderHandler
-                  // sent it already
-                  established(ch);
-                } else {
-                  final Throwable error = future.cause();
-                  scheduleRelogin(error);
-                  failInit(ch, toIOE(error));
+            NettyFutureUtils
+              .consume(connectionHeaderPromise.addListener(new FutureListener<Boolean>() {
+                @Override
+                public void operationComplete(Future<Boolean> future) throws Exception {
+                  if (future.isSuccess()) {
+                    ChannelPipeline p = ch.pipeline();
+                    p.remove(ReadTimeoutHandler.class);
+                    p.remove(NettyHBaseRpcConnectionHeaderHandler.class);
+                    // don't send connection header, NettyHbaseRpcConnectionHeaderHandler
+                    // sent it already
+                    established(ch);
+                  } else {
+                    final Throwable error = future.cause();
+                    scheduleRelogin(error);
+                    failInit(ch, toIOE(error));
+                  }
                 }
-              }
-            });
+              }));
           } else {
             // send the connection header to server
-            ch.write(connectionHeaderWithLength.retainedDuplicate());
+            NettyFutureUtils.safeWrite(ch, connectionHeaderWithLength.retainedDuplicate());
             established(ch);
           }
         } else {
@@ -263,7 +266,7 @@ class NettyRpcConnection extends RpcConnection {
           failInit(ch, toIOE(error));
         }
       }
-    });
+    }));
   }
 
   private void connect() throws UnknownHostException {
@@ -285,12 +288,12 @@ class NettyRpcConnection extends RpcConnection {
             rpcClient.failedServers.addToFailedServers(remoteId.getAddress(), future.cause());
             return;
           }
-          ch.writeAndFlush(connectionHeaderPreamble.retainedDuplicate());
+          NettyFutureUtils.safeWriteAndFlush(ch, connectionHeaderPreamble.retainedDuplicate());
           if (useSasl) {
             saslNegotiate(ch);
           } else {
             // send the connection header to server
-            ch.write(connectionHeaderWithLength.retainedDuplicate());
+            NettyFutureUtils.safeWrite(ch, connectionHeaderWithLength.retainedDuplicate());
             established(ch);
           }
         }
@@ -322,8 +325,7 @@ class NettyRpcConnection extends RpcConnection {
             connect();
           }
           scheduleTimeoutTask(call);
-          channel.writeAndFlush(call).addListener(new ChannelFutureListener() {
-
+          NettyFutureUtils.addListener(channel.writeAndFlush(call), new ChannelFutureListener() {
             @Override
             public void operationComplete(ChannelFuture future) throws Exception {
               // Fail the call if we failed to write it out. This usually because the channel is
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcDuplexHandler.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcDuplexHandler.java
index fe32189f81b..700093a3027 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcDuplexHandler.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcDuplexHandler.java
@@ -31,7 +31,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import org.apache.hbase.thirdparty.com.google.protobuf.Message;
-import org.apache.hbase.thirdparty.com.google.protobuf.Message.Builder;
 import org.apache.hbase.thirdparty.com.google.protobuf.TextFormat;
 import org.apache.hbase.thirdparty.io.netty.buffer.ByteBuf;
 import org.apache.hbase.thirdparty.io.netty.buffer.ByteBufInputStream;
@@ -168,7 +167,7 @@ class NettyRpcDuplexHandler extends ChannelDuplexHandler {
     }
     Message value;
     if (call.responseDefaultType != null) {
-      Builder builder = call.responseDefaultType.newBuilderForType();
+      Message.Builder builder = call.responseDefaultType.newBuilderForType();
       builder.mergeDelimitedFrom(in);
       value = builder.build();
     } else {
@@ -202,7 +201,7 @@ class NettyRpcDuplexHandler extends ChannelDuplexHandler {
     }
   }
 
-  private void cleanupCalls(ChannelHandlerContext ctx, IOException error) {
+  private void cleanupCalls(IOException error) {
     for (Call call : id2Call.values()) {
       call.setException(error);
     }
@@ -212,7 +211,7 @@ class NettyRpcDuplexHandler extends ChannelDuplexHandler {
   @Override
   public void channelInactive(ChannelHandlerContext ctx) throws Exception {
     if (!id2Call.isEmpty()) {
-      cleanupCalls(ctx, new ConnectionClosedException("Connection closed"));
+      cleanupCalls(new ConnectionClosedException("Connection closed"));
     }
     conn.shutdown();
     ctx.fireChannelInactive();
@@ -221,7 +220,7 @@ class NettyRpcDuplexHandler extends ChannelDuplexHandler {
   @Override
   public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
     if (!id2Call.isEmpty()) {
-      cleanupCalls(ctx, IPCUtil.toIOE(cause));
+      cleanupCalls(IPCUtil.toIOE(cause));
     }
     conn.shutdown();
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/RpcClient.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/RpcClient.java
index 6ecff49e52b..045216e8881 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/RpcClient.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/RpcClient.java
@@ -90,8 +90,8 @@ public interface RpcClient extends Closeable {
   void close();
 
   /**
-   * @return true when this client uses a {@link org.apache.hadoop.hbase.codec.Codec} and so
-   *         supports cell blocks.
+   * Return true when this client uses a {@link org.apache.hadoop.hbase.codec.Codec} and so supports
+   * cell blocks.
    */
   boolean hasCellBlockSupport();
 }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/master/RegionState.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/master/RegionState.java
index 2b0f2f4509e..4fc6cac029f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/master/RegionState.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/master/RegionState.java
@@ -384,6 +384,7 @@ public class RegionState {
   /**
    * A slower (but more easy-to-read) stringification
    */
+  @SuppressWarnings("JavaUtilDate")
   public String toDescriptiveString() {
     long relTime = EnvironmentEdgeManager.currentTime() - stamp;
     return hri.getRegionNameAsString() + " state=" + state + ", ts=" + new Date(stamp) + " ("
@@ -417,12 +418,13 @@ public class RegionState {
    */
   @Override
   public boolean equals(Object obj) {
-    if (this == obj) return true;
-    if (obj == null || getClass() != obj.getClass()) {
+    if (this == obj) {
+      return true;
+    }
+    if (!(obj instanceof RegionState)) {
       return false;
     }
     RegionState tmp = (RegionState) obj;
-
     return RegionInfo.COMPARATOR.compare(tmp.hri, hri) == 0 && tmp.state == state
       && ((serverName != null && serverName.equals(tmp.serverName))
         || (tmp.serverName == null && serverName == null));
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufMagic.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufMagic.java
index 15a196cbe5b..4a285ba40be 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufMagic.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufMagic.java
@@ -35,8 +35,7 @@ public class ProtobufMagic {
   public static final byte[] PB_MAGIC = new byte[] { 'P', 'B', 'U', 'F' };
 
   /**
-   * @param bytes Bytes to check.
-   * @return True if passed <code>bytes</code> has {@link #PB_MAGIC} for a prefix.
+   * Returns True if passed <code>bytes</code> has {@link #PB_MAGIC} for a prefix.
    */
   public static boolean isPBMagicPrefix(final byte[] bytes) {
     if (bytes == null) return false;
@@ -66,12 +65,7 @@ public class ProtobufMagic {
     return length1 - length2;
   }
 
-  /**
-   * @param bytes  Bytes to check.
-   * @param offset offset to start at
-   * @param len    length to use
-   * @return True if passed <code>bytes</code> has {@link #PB_MAGIC} for a prefix.
-   */
+  /** Returns True if passed <code>bytes</code> has {@link #PB_MAGIC} for a prefix. */
   public static boolean isPBMagicPrefix(final byte[] bytes, int offset, int len) {
     if (bytes == null || len < PB_MAGIC.length) return false;
     return compareTo(PB_MAGIC, 0, PB_MAGIC.length, bytes, offset, PB_MAGIC.length) == 0;
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java
index 76ce56318ed..f8820306699 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java
@@ -43,7 +43,6 @@ import java.util.function.Function;
 import java.util.stream.Collectors;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.Cell.Type;
 import org.apache.hadoop.hbase.CellBuilderType;
 import org.apache.hadoop.hbase.CellScanner;
 import org.apache.hadoop.hbase.CellUtil;
@@ -194,6 +193,7 @@ public final class ProtobufUtil {
   }
 
   /**
+   * Check for {@link ProtobufMagic#PB_MAGIC}
    * @param bytes Bytes to check.
    * @return True if passed <code>bytes</code> has {@link ProtobufMagic#PB_MAGIC} for a prefix.
    */
@@ -202,6 +202,7 @@ public final class ProtobufUtil {
   }
 
   /**
+   * Check for {@link ProtobufMagic#PB_MAGIC}
    * @param bytes  Bytes to check.
    * @param offset offset to start at
    * @param len    length to use
@@ -212,6 +213,7 @@ public final class ProtobufUtil {
   }
 
   /**
+   * Check for {@link ProtobufMagic#PB_MAGIC}
    * @param bytes bytes to check
    * @throws DeserializationException if we are missing the pb magic prefix
    */
@@ -523,7 +525,7 @@ public final class ProtobufUtil {
             } else {
               put.add(cellBuilder.clear().setRow(put.getRow()).setFamily(family)
                 .setQualifier(qv.hasQualifier() ? qv.getQualifier().toByteArray() : null)
-                .setTimestamp(ts).setType(Type.Put)
+                .setTimestamp(ts).setType(Cell.Type.Put)
                 .setValue(qv.hasValue() ? qv.getValue().toByteArray() : null).build());
             }
           }
@@ -677,9 +679,8 @@ public final class ProtobufUtil {
   }
 
   /**
-   * Convert a protocol buffer Mutate to an Append n * @param proto the protocol buffer Mutate to
-   * convert
-   * @return the converted client Append n
+   * Convert a protocol buffer Mutate to an Append
+   * @return the converted client Append
    */
   public static Append toAppend(final MutationProto proto, final CellScanner cellScanner)
     throws IOException {
@@ -696,8 +697,7 @@ public final class ProtobufUtil {
 
   /**
    * Convert a protocol buffer Mutate to an Increment
-   * @param proto the protocol buffer Mutate to convert
-   * @return the converted client Increment n
+   * @return the converted client Increment
    */
   public static Increment toIncrement(final MutationProto proto, final CellScanner cellScanner)
     throws IOException {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/QuotaRetriever.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/QuotaRetriever.java
index 728959e0a0c..1dd5bf275bb 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/QuotaRetriever.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/QuotaRetriever.java
@@ -19,8 +19,8 @@ package org.apache.hadoop.hbase.quotas;
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.util.ArrayDeque;
 import java.util.Iterator;
-import java.util.LinkedList;
 import java.util.Objects;
 import java.util.Queue;
 import org.apache.hadoop.conf.Configuration;
@@ -43,7 +43,7 @@ import org.slf4j.LoggerFactory;
 public class QuotaRetriever implements Closeable, Iterable<QuotaSettings> {
   private static final Logger LOG = LoggerFactory.getLogger(QuotaRetriever.class);
 
-  private final Queue<QuotaSettings> cache = new LinkedList<>();
+  private final Queue<QuotaSettings> cache = new ArrayDeque<>();
   private ResultScanner scanner;
   /**
    * Connection to use. Could pass one in and have this class use it but this class wants to be
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/SpaceLimitSettings.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/SpaceLimitSettings.java
index 878cbe871e5..4a230338598 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/SpaceLimitSettings.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/SpaceLimitSettings.java
@@ -23,7 +23,7 @@ import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.yetus.audience.InterfaceStability;
 
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetQuotaRequest.Builder;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetQuotaRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.QuotaProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.QuotaProtos.SpaceLimitRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.QuotaProtos.SpaceQuota;
@@ -113,7 +113,7 @@ class SpaceLimitSettings extends QuotaSettings {
   }
 
   @Override
-  protected void setupSetQuotaRequest(Builder builder) {
+  protected void setupSetQuotaRequest(SetQuotaRequest.Builder builder) {
     // TableName/Namespace are serialized in QuotaSettings
     builder.setSpaceLimit(proto);
   }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSink.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSink.java
index 9da498c0452..f954cdc9d9b 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSink.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSink.java
@@ -42,6 +42,7 @@ public class ReplicationLoadSink {
   }
 
   /**
+   * Get the timestamp of the last applied operation.
    * @deprecated Since hbase-2.0.0. Will be removed in 3.0.0.
    * @see #getTimestampsOfLastAppliedOp()
    */
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSource.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSource.java
index 15cbda439a5..49c75240778 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSource.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/replication/ReplicationLoadSource.java
@@ -68,6 +68,7 @@ public final class ReplicationLoadSource {
   }
 
   /**
+   * Get the timestamp of the last shipped operation.
    * @deprecated Since 2.0.0. Will be removed in 3.0.0.
    * @see #getTimestampOfLastShippedOp()
    */
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/NettyHBaseRpcConnectionHeaderHandler.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/NettyHBaseRpcConnectionHeaderHandler.java
index 20197912dcb..cb680b51724 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/NettyHBaseRpcConnectionHeaderHandler.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/NettyHBaseRpcConnectionHeaderHandler.java
@@ -19,6 +19,7 @@ package org.apache.hadoop.hbase.security;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.io.crypto.aes.CryptoAES;
+import org.apache.hadoop.hbase.util.NettyFutureUtils;
 import org.apache.yetus.audience.InterfaceAudience;
 
 import org.apache.hbase.thirdparty.io.netty.buffer.ByteBuf;
@@ -66,15 +67,14 @@ public class NettyHBaseRpcConnectionHeaderHandler extends SimpleChannelInboundHa
       // replace the Sasl handler with Crypto AES handler
       setupCryptoAESHandler(ctx.pipeline(), cryptoAES);
     }
-
-    saslPromise.setSuccess(true);
+    NettyFutureUtils.consume(saslPromise.setSuccess(true));
   }
 
   @Override
   public void handlerAdded(ChannelHandlerContext ctx) {
     try {
       // send the connection header to server first
-      ctx.writeAndFlush(connectionHeaderWithLength.retainedDuplicate());
+      NettyFutureUtils.safeWriteAndFlush(ctx, connectionHeaderWithLength.retainedDuplicate());
     } catch (Exception e) {
       // the exception thrown by handlerAdded will not be passed to the exceptionCaught below
       // because netty will remove a handler if handlerAdded throws an exception.
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/SaslUtil.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/SaslUtil.java
index c2dc1042c91..dfb0a49db4a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/SaslUtil.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/SaslUtil.java
@@ -29,6 +29,8 @@ import org.apache.yetus.audience.InterfaceAudience;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import org.apache.hbase.thirdparty.com.google.common.base.Splitter;
+
 @InterfaceAudience.Private
 public class SaslUtil {
   private static final Logger LOG = LoggerFactory.getLogger(SaslUtil.class);
@@ -62,7 +64,7 @@ public class SaslUtil {
 
   /** Splitting fully qualified Kerberos name into parts */
   public static String[] splitKerberosName(String fullName) {
-    return fullName.split("[/@]");
+    return Splitter.onPattern("[/@]").splitToStream(fullName).toArray(String[]::new);
   }
 
   public static String encodeIdentifier(byte[] identifier) {
@@ -93,6 +95,7 @@ public class SaslUtil {
   }
 
   /**
+   * Initialize SASL properties for a given RPC protection level.
    * @param rpcProtection Value of 'hbase.rpc.protection' configuration.
    * @return Map with values for SASL properties.
    */
@@ -101,10 +104,9 @@ public class SaslUtil {
     if (rpcProtection.isEmpty()) {
       saslQop = QualityOfProtection.AUTHENTICATION.getSaslQop();
     } else {
-      String[] qops = rpcProtection.split(",");
       StringBuilder saslQopBuilder = new StringBuilder();
-      for (int i = 0; i < qops.length; ++i) {
-        QualityOfProtection qop = getQop(qops[i]);
+      for (String s : Splitter.on(',').split(rpcProtection)) {
+        QualityOfProtection qop = getQop(s);
         saslQopBuilder.append(",").append(qop.getSaslQop());
       }
       saslQop = saslQopBuilder.substring(1); // remove first ','
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlClient.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlClient.java
index c6c0c2ecde5..e30041d46c4 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlClient.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlClient.java
@@ -29,12 +29,8 @@ import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.ZooKeeperConnectionException;
 import org.apache.hadoop.hbase.client.Admin;
 import org.apache.hadoop.hbase.client.Connection;
-import org.apache.hadoop.hbase.client.Table;
 import org.apache.hadoop.hbase.client.TableDescriptor;
 import org.apache.hadoop.hbase.client.security.SecurityCapability;
-import org.apache.hadoop.hbase.ipc.CoprocessorRpcChannel;
-import org.apache.hadoop.hbase.protobuf.generated.AccessControlProtos;
-import org.apache.hadoop.hbase.protobuf.generated.AccessControlProtos.AccessControlService.BlockingInterface;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.yetus.audience.InterfaceAudience;
 
@@ -66,17 +62,17 @@ public class AccessControlClient {
       .contains(SecurityCapability.CELL_AUTHORIZATION);
   }
 
-  private static BlockingInterface getAccessControlServiceStub(Table ht) throws IOException {
-    CoprocessorRpcChannel service = ht.coprocessorService(HConstants.EMPTY_START_ROW);
-    BlockingInterface protocol = AccessControlProtos.AccessControlService.newBlockingStub(service);
-    return protocol;
-  }
-
   /**
    * Grants permission on the specified table for the specified user
-   * @param connection The Connection instance to use nnnn * @param mergeExistingPermissions If set
-   *                   to false, later granted permissions will override previous granted
-   *                   permissions. otherwise, it'll merge with previous granted permissions. nn
+   * @param connection               The Connection instance to use
+   * @param tableName                the table name
+   * @param userName                 the user name
+   * @param family                   the column family
+   * @param qual                     the column qualifier
+   * @param mergeExistingPermissions If set to false, later granted permissions will override
+   *                                 previous granted permissions. otherwise, it'll merge with
+   *                                 previous granted permissions.
+   * @param actions                  the actions
    */
   private static void grant(Connection connection, final TableName tableName, final String userName,
     final byte[] family, final byte[] qual, boolean mergeExistingPermissions,
@@ -89,7 +85,12 @@ public class AccessControlClient {
   /**
    * Grants permission on the specified table for the specified user. If permissions for a specified
    * user exists, later granted permissions will override previous granted permissions.
-   * @param connection The Connection instance to use nnnnnn
+   * @param connection The Connection instance to use
+   * @param tableName  the table name
+   * @param userName   the user name
+   * @param family     the column family
+   * @param qual       the column qualifier
+   * @param actions    the actions
    */
   public static void grant(Connection connection, final TableName tableName, final String userName,
     final byte[] family, final byte[] qual, final Permission.Action... actions) throws Throwable {
@@ -97,9 +98,14 @@ public class AccessControlClient {
   }
 
   /**
-   * Grants permission on the specified namespace for the specified user. nnn * @param
-   * mergeExistingPermissions If set to false, later granted permissions will override previous
-   * granted permissions. otherwise, it'll merge with previous granted permissions. nn
+   * Grants permission on the specified namespace for the specified user.
+   * @param connection               The Connection instance to use
+   * @param namespace                the namespace
+   * @param userName                 the user name
+   * @param mergeExistingPermissions If set to false, later granted permissions will override
+   *                                 previous granted permissions. otherwise, it'll merge with
+   *                                 previous granted permissions.
+   * @param actions                  the actions
    */
   private static void grant(Connection connection, final String namespace, final String userName,
     boolean mergeExistingPermissions, final Permission.Action... actions) throws Throwable {
@@ -112,7 +118,10 @@ public class AccessControlClient {
    * Grants permission on the specified namespace for the specified user. If permissions on the
    * specified namespace exists, later granted permissions will override previous granted
    * permissions.
-   * @param connection The Connection instance to use nnnn
+   * @param connection The Connection instance to use
+   * @param namespace  the namespace
+   * @param userName   the user name
+   * @param actions    the actions
    */
   public static void grant(Connection connection, final String namespace, final String userName,
     final Permission.Action... actions) throws Throwable {
@@ -120,9 +129,13 @@ public class AccessControlClient {
   }
 
   /**
-   * Grant global permissions for the specified user. nn * @param mergeExistingPermissions If set to
-   * false, later granted permissions will override previous granted permissions. otherwise, it'll
-   * merge with previous granted permissions. nn
+   * Grant global permissions for the specified user.
+   * @param connection               The Connection instance to use
+   * @param userName                 the user name
+   * @param mergeExistingPermissions If set to false, later granted permissions will override
+   *                                 previous granted permissions. otherwise, it'll merge with
+   *                                 previous granted permissions.
+   * @param actions                  the actions
    */
   private static void grant(Connection connection, final String userName,
     boolean mergeExistingPermissions, final Permission.Action... actions) throws Throwable {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlUtil.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlUtil.java
index 6496aaa0bb8..1fa1bdfd21c 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlUtil.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlUtil.java
@@ -40,9 +40,6 @@ import org.apache.hbase.thirdparty.com.google.common.collect.ArrayListMultimap;
 import org.apache.hbase.thirdparty.com.google.common.collect.ListMultimap;
 import org.apache.hbase.thirdparty.com.google.common.collect.Lists;
 
-/**
- * @since 2.0.0
- */
 @InterfaceAudience.Private
 public class AccessControlUtil {
   private AccessControlUtil() {
@@ -223,13 +220,12 @@ public class AccessControlUtil {
    */
   public static TablePermission toTablePermission(AccessControlProtos.TablePermission proto) {
     Permission.Action[] actions = toPermissionActions(proto.getActionList());
-    TableName table = null;
-    byte[] qualifier = null;
-    byte[] family = null;
     if (!proto.hasTableName()) {
       throw new IllegalStateException("TableName cannot be empty");
     }
-    table = ProtobufUtil.toTableName(proto.getTableName());
+    TableName table = ProtobufUtil.toTableName(proto.getTableName());
+    byte[] family = null;
+    byte[] qualifier = null;
     if (proto.hasFamily()) {
       family = proto.getFamily().toByteArray();
     }
@@ -262,13 +258,12 @@ public class AccessControlUtil {
     if (proto.getType() == AccessControlProtos.Permission.Type.Table) {
       AccessControlProtos.TablePermission perm = proto.getTablePermission();
       Permission.Action[] actions = toPermissionActions(perm.getActionList());
-      byte[] qualifier = null;
-      byte[] family = null;
-      TableName table = null;
       if (!perm.hasTableName()) {
         throw new IllegalStateException("TableName cannot be empty");
       }
-      table = ProtobufUtil.toTableName(perm.getTableName());
+      TableName table = ProtobufUtil.toTableName(perm.getTableName());
+      byte[] family = null;
+      byte[] qualifier = null;
       if (perm.hasFamily()) {
         family = perm.getFamily().toByteArray();
       }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/ShadedAccessControlUtil.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/ShadedAccessControlUtil.java
index b6df2c94a04..cf7c797c98a 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/ShadedAccessControlUtil.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/ShadedAccessControlUtil.java
@@ -21,7 +21,6 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import org.apache.hadoop.hbase.TableName;
-import org.apache.hadoop.hbase.security.access.Permission.Action;
 import org.apache.yetus.audience.InterfaceAudience;
 
 import org.apache.hbase.thirdparty.com.google.common.collect.ArrayListMultimap;
@@ -32,7 +31,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.AccessControlProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AccessControlProtos.GetUserPermissionsResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AccessControlProtos.GrantRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AccessControlProtos.HasUserPermissionsRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.AccessControlProtos.Permission.Type;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AccessControlProtos.RevokeRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos;
 
@@ -122,12 +120,12 @@ public class ShadedAccessControlUtil {
 
     if (proto.getType() == AccessControlProtos.Permission.Type.Global) {
       AccessControlProtos.GlobalPermission perm = proto.getGlobalPermission();
-      Action[] actions = toPermissionActions(perm.getActionList());
+      Permission.Action[] actions = toPermissionActions(perm.getActionList());
       return Permission.newBuilder().withActions(actions).build();
     }
     if (proto.getType() == AccessControlProtos.Permission.Type.Namespace) {
       AccessControlProtos.NamespacePermission perm = proto.getNamespacePermission();
-      Action[] actions = toPermissionActions(perm.getActionList());
+      Permission.Action[] actions = toPermissionActions(perm.getActionList());
 
       if (!proto.hasNamespacePermission()) {
         throw new IllegalStateException("Namespace must not be empty in NamespacePermission");
@@ -137,7 +135,7 @@ public class ShadedAccessControlUtil {
     }
     if (proto.getType() == AccessControlProtos.Permission.Type.Table) {
       AccessControlProtos.TablePermission perm = proto.getTablePermission();
-      Action[] actions = toPermissionActions(perm.getActionList());
+      Permission.Action[] actions = toPermissionActions(perm.getActionList());
 
       byte[] qualifier = null;
       byte[] family = null;
@@ -292,14 +290,14 @@ public class ShadedAccessControlUtil {
     }
     if (request.getNamespace() != null && !request.getNamespace().isEmpty()) {
       builder.setNamespaceName(ByteString.copyFromUtf8(request.getNamespace()));
-      builder.setType(Type.Namespace);
+      builder.setType(AccessControlProtos.Permission.Type.Namespace);
     }
     if (request.getTableName() != null) {
       builder.setTableName(toProtoTableName(request.getTableName()));
-      builder.setType(Type.Table);
+      builder.setType(AccessControlProtos.Permission.Type.Table);
     }
     if (!builder.hasType()) {
-      builder.setType(Type.Global);
+      builder.setType(AccessControlProtos.Permission.Type.Global);
     }
     if (request.getFamily() != null && request.getFamily().length > 0) {
       builder.setColumnFamily(ByteString.copyFrom(request.getFamily()));
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/TablePermission.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/TablePermission.java
index e0a12c7d431..65ebbef7da0 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/TablePermission.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/TablePermission.java
@@ -141,11 +141,11 @@ public class TablePermission extends Permission {
       return false;
     }
 
-    if (family != null && !(CellUtil.matchingFamily(kv, family))) {
+    if (family != null && !CellUtil.matchingFamily(kv, family)) {
       return false;
     }
 
-    if (qualifier != null && !(CellUtil.matchingQualifier(kv, qualifier))) {
+    if (qualifier != null && !CellUtil.matchingQualifier(kv, qualifier)) {
       return false;
     }
 
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityClient.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityClient.java
index cca5e8362ef..0c9dc35d75d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityClient.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityClient.java
@@ -153,7 +153,7 @@ public class VisibilityClient {
   }
 
   /**
-   * nn * @return labels, the given user is globally authorized for. n * @deprecated Use
+   * Returns labels, the given user is globally authorized for. n * @deprecated Use
    * {@link #getAuths(Connection,String)} instead.
    */
   @Deprecated
@@ -164,8 +164,10 @@ public class VisibilityClient {
   }
 
   /**
-   * @param connection the Connection instance to use. n * @return labels, the given user is
-   *                   globally authorized for. n
+   * Get the authorization for a given user
+   * @param connection the Connection instance to use
+   * @param user       the user
+   * @return labels the given user is globally authorized for
    */
   public static GetAuthsResponse getAuths(Connection connection, final String user)
     throws Throwable {
@@ -196,10 +198,11 @@ public class VisibilityClient {
   }
 
   /**
-   * Retrieve the list of visibility labels defined in the system. n * @param regex The regular
-   * expression to filter which labels are returned.
-   * @return labels The list of visibility labels defined in the system. n * @deprecated Use
-   *         {@link #listLabels(Connection,String)} instead.
+   * Retrieve the list of visibility labels defined in the system.
+   * @param conf  the configuration to use
+   * @param regex The regular expression to filter which labels are returned.
+   * @return labels The list of visibility labels defined in the system.
+   * @deprecated Use {@link #listLabels(Connection,String)} instead.
    */
   @Deprecated
   public static ListLabelsResponse listLabels(Configuration conf, final String regex)
@@ -285,7 +288,7 @@ public class VisibilityClient {
             setAuthReqBuilder.setUser(ByteStringer.wrap(Bytes.toBytes(user)));
             for (String auth : auths) {
               if (auth.length() > 0) {
-                setAuthReqBuilder.addAuth((ByteString.copyFromUtf8(auth)));
+                setAuthReqBuilder.addAuth(ByteString.copyFromUtf8(auth));
               }
             }
             if (setOrClear) {
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ProtobufUtil.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ProtobufUtil.java
index cb063938848..1d296229fcf 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ProtobufUtil.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/ProtobufUtil.java
@@ -49,7 +49,6 @@ import org.apache.hadoop.hbase.ByteBufferExtendedCell;
 import org.apache.hadoop.hbase.CacheEvictionStats;
 import org.apache.hadoop.hbase.CacheEvictionStatsBuilder;
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.Cell.Type;
 import org.apache.hadoop.hbase.CellBuilderType;
 import org.apache.hadoop.hbase.CellScanner;
 import org.apache.hadoop.hbase.CellUtil;
@@ -304,25 +303,18 @@ public final class ProtobufUtil {
     return Bytes.add(PB_MAGIC, bytes);
   }
 
-  /**
-   * @param bytes Bytes to check.
-   * @return True if passed <code>bytes</code> has {@link ProtobufMagic#PB_MAGIC} for a prefix.
-   */
+  /** Returns True if passed <code>bytes</code> has {@link ProtobufMagic#PB_MAGIC} for a prefix. */
   public static boolean isPBMagicPrefix(final byte[] bytes) {
     return ProtobufMagic.isPBMagicPrefix(bytes);
   }
 
-  /**
-   * @param bytes  Bytes to check.
-   * @param offset offset to start at
-   * @param len    length to use
-   * @return True if passed <code>bytes</code> has {@link ProtobufMagic#PB_MAGIC} for a prefix.
-   */
+  /** Returns True if passed <code>bytes</code> has {@link ProtobufMagic#PB_MAGIC} for a prefix. */
   public static boolean isPBMagicPrefix(final byte[] bytes, int offset, int len) {
     return ProtobufMagic.isPBMagicPrefix(bytes, offset, len);
   }
 
   /**
+   * Expect the {@link ProtobufMagic#PB_MAGIC} or throw an exception.
    * @param bytes bytes to check
    * @throws DeserializationException if we are missing the pb magic prefix
    */
@@ -683,7 +675,7 @@ public final class ProtobufUtil {
             } else {
               put.add(cellBuilder.clear().setRow(put.getRow()).setFamily(family)
                 .setQualifier(qv.hasQualifier() ? qv.getQualifier().toByteArray() : null)
-                .setTimestamp(ts).setType(Type.Put)
+                .setTimestamp(ts).setType(Cell.Type.Put)
                 .setValue(qv.hasValue() ? qv.getValue().toByteArray() : null).build());
             }
           }
@@ -840,9 +832,9 @@ public final class ProtobufUtil {
   }
 
   /**
-   * Convert a protocol buffer Mutate to an Append n * @param proto the protocol buffer Mutate to
-   * convert
-   * @return the converted client Append n
+   * Convert a protocol buffer Mutate to an Append
+   * @param proto the protocol buffer Mutate to convert
+   * @return the converted client Append
    */
   public static Append toAppend(final MutationProto proto, final CellScanner cellScanner)
     throws IOException {
@@ -860,7 +852,7 @@ public final class ProtobufUtil {
   /**
    * Convert a protocol buffer Mutate to an Increment
    * @param proto the protocol buffer Mutate to convert
-   * @return the converted client Increment n
+   * @return the converted client Increment
    */
   public static Increment toIncrement(final MutationProto proto, final CellScanner cellScanner)
     throws IOException {
@@ -1803,9 +1795,6 @@ public final class ProtobufUtil {
     return rl.getReadRequestsCount() + rl.getWriteRequestsCount();
   }
 
-  /**
-   * @param m Message to get delimited pb serialization of (with pb magic prefix)
-   */
   public static byte[] toDelimitedByteArray(final Message m) throws IOException {
     // Allocate arbitrary big size so we avoid resizing.
     ByteArrayOutputStream baos = new ByteArrayOutputStream(4096);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/RequestConverter.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/RequestConverter.java
index 0ca16009d6c..7ef234f6b7f 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/RequestConverter.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/RequestConverter.java
@@ -900,6 +900,7 @@ public final class RequestConverter {
   }
 
   /**
+   * Create a protocol buffer GetRegionInfoRequest,
    * @param regionName             the name of the region to get info
    * @param includeCompactionState indicate if the compaction state is requested
    * @param includeBestSplitRow    indicate if the bestSplitRow is requested
@@ -1121,7 +1122,7 @@ public final class RequestConverter {
   public static ModifyColumnRequest buildModifyColumnRequest(final TableName tableName,
     final ColumnFamilyDescriptor column, final long nonceGroup, final long nonce) {
     ModifyColumnRequest.Builder builder = ModifyColumnRequest.newBuilder();
-    builder.setTableName(ProtobufUtil.toProtoTableName((tableName)));
+    builder.setTableName(ProtobufUtil.toProtoTableName(tableName));
     builder.setColumnFamilies(ProtobufUtil.toColumnFamilySchema(column));
     builder.setNonceGroup(nonceGroup);
     builder.setNonce(nonce);
@@ -1133,7 +1134,7 @@ public final class RequestConverter {
     final long nonce) {
     ModifyColumnStoreFileTrackerRequest.Builder builder =
       ModifyColumnStoreFileTrackerRequest.newBuilder();
-    builder.setTableName(ProtobufUtil.toProtoTableName((tableName)));
+    builder.setTableName(ProtobufUtil.toProtoTableName(tableName));
     builder.setFamily(ByteString.copyFrom(family));
     builder.setDstSft(dstSFT);
     builder.setNonceGroup(nonceGroup);
@@ -1255,7 +1256,7 @@ public final class RequestConverter {
   public static DisableTableRequest buildDisableTableRequest(final TableName tableName,
     final long nonceGroup, final long nonce) {
     DisableTableRequest.Builder builder = DisableTableRequest.newBuilder();
-    builder.setTableName(ProtobufUtil.toProtoTableName((tableName)));
+    builder.setTableName(ProtobufUtil.toProtoTableName(tableName));
     builder.setNonceGroup(nonceGroup);
     builder.setNonce(nonce);
     return builder.build();
@@ -1284,7 +1285,7 @@ public final class RequestConverter {
   public static ModifyTableRequest buildModifyTableRequest(final TableName tableName,
     final TableDescriptor tableDesc, final long nonceGroup, final long nonce) {
     ModifyTableRequest.Builder builder = ModifyTableRequest.newBuilder();
-    builder.setTableName(ProtobufUtil.toProtoTableName((tableName)));
+    builder.setTableName(ProtobufUtil.toProtoTableName(tableName));
     builder.setTableSchema(ProtobufUtil.toTableSchema(tableDesc));
     builder.setNonceGroup(nonceGroup);
     builder.setNonce(nonce);
@@ -1295,7 +1296,7 @@ public final class RequestConverter {
     final TableName tableName, final String dstSFT, final long nonceGroup, final long nonce) {
     ModifyTableStoreFileTrackerRequest.Builder builder =
       ModifyTableStoreFileTrackerRequest.newBuilder();
-    builder.setTableName(ProtobufUtil.toProtoTableName((tableName)));
+    builder.setTableName(ProtobufUtil.toProtoTableName(tableName));
     builder.setDstSft(dstSFT);
     builder.setNonceGroup(nonceGroup);
     builder.setNonce(nonce);
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/util/Writables.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/util/Writables.java
index 7ebbbf44ceb..091515c325e 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/util/Writables.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/util/Writables.java
@@ -34,6 +34,7 @@ import org.apache.yetus.audience.InterfaceAudience;
 @InterfaceAudience.Private
 public class Writables {
   /**
+   * Get the Writable's contents as a byte array
    * @param w writable
    * @return The bytes of <code>w</code> gotten by running its
    *         {@link Writable#write(java.io.DataOutput)} method.
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ReadOnlyZKClient.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ReadOnlyZKClient.java
index 96170736208..979094fda80 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ReadOnlyZKClient.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ReadOnlyZKClient.java
@@ -183,6 +183,8 @@ public final class ReadOnlyZKClient implements Closeable {
               try {
                 zk.close();
               } catch (InterruptedException e) {
+                // Restore interrupt status
+                Thread.currentThread().interrupt();
               }
             }
             if (ZKTask.this.delay(retryIntervalMs, maxRetries)) {
@@ -303,6 +305,8 @@ public final class ReadOnlyZKClient implements Closeable {
       try {
         zookeeper.close();
       } catch (InterruptedException e) {
+        // Restore interrupt status
+        Thread.currentThread().interrupt();
       }
       zookeeper = null;
     }
diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKMetadata.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKMetadata.java
index f0fae958a66..b795ad45aa1 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKMetadata.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKMetadata.java
@@ -54,7 +54,7 @@ public class ZKMetadata {
     pos = Bytes.putInt(newData, pos, idLength);
     pos = Bytes.putBytes(newData, pos, id, 0, id.length);
     pos = Bytes.putBytes(newData, pos, salt, 0, salt.length);
-    pos = Bytes.putBytes(newData, pos, data, 0, data.length);
+    Bytes.putBytes(newData, pos, data, 0, data.length);
     return newData;
   }
 
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/TestHTableDescriptor.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/TestHTableDescriptor.java
index 2bfaa2de788..cdf043dad76 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/TestHTableDescriptor.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/TestHTableDescriptor.java
@@ -86,11 +86,7 @@ public class TestHTableDescriptor {
 
     // Try more spec.
     String spec = "hdfs:///foo.jar|com.foo.FooRegionObserver|1001|arg1=1,arg2=2";
-    try {
-      htd.addCoprocessorWithSpec(spec);
-    } catch (IllegalArgumentException iae) {
-      fail();
-    }
+    htd.addCoprocessorWithSpec(spec);
 
     // Try double add of same coprocessor
     try {
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncProcess.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncProcess.java
index 89634924e57..de6d6012322 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncProcess.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncProcess.java
@@ -28,7 +28,6 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Random;
@@ -428,6 +427,8 @@ public class TestAsyncProcess {
             try {
               Thread.sleep(sleep);
             } catch (InterruptedException e) {
+              // Restore interrupt status
+              Thread.currentThread().interrupt();
             }
           }
           return mr;
@@ -525,15 +526,14 @@ public class TestAsyncProcess {
   @Test
   public void testListRowAccess() {
     int count = 10;
-    List<String> values = new LinkedList<>();
+    List<String> values = new ArrayList<>();
     for (int i = 0; i != count; ++i) {
       values.add(String.valueOf(i));
     }
 
-    ListRowAccess<String> taker = new ListRowAccess(values);
+    ListRowAccess<String> taker = new ListRowAccess<>(values);
     assertEquals(count, taker.size());
 
-    int restoreCount = 0;
     int takeCount = 0;
     Iterator<String> it = taker.iterator();
     while (it.hasNext()) {
@@ -1330,7 +1330,7 @@ public class TestAsyncProcess {
     MyAsyncProcess ap = new MyAsyncProcess(conn, copyConf);
     try (HTable ht = (HTable) conn.getTable(DUMMY_TABLE)) {
       ht.multiAp = ap;
-      List<Get> gets = new LinkedList<>();
+      List<Get> gets = new ArrayList<>();
       gets.add(new Get(DUMMY_BYTES_1));
       gets.add(new Get(DUMMY_BYTES_2));
       try {
@@ -1349,7 +1349,7 @@ public class TestAsyncProcess {
       assertEquals(readTimeout, ap.previousTimeout);
       ap.previousTimeout = -1;
 
-      List<Delete> deletes = new LinkedList<>();
+      List<Delete> deletes = new ArrayList<>();
       deletes.add(new Delete(DUMMY_BYTES_1));
       deletes.add(new Delete(DUMMY_BYTES_2));
       ht.delete(deletes);
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableRpcPriority.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableRpcPriority.java
index 7d6ef3f0c4e..d1a5dcc8383 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableRpcPriority.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableRpcPriority.java
@@ -45,7 +45,6 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.Cell.Type;
 import org.apache.hadoop.hbase.CellBuilderFactory;
 import org.apache.hadoop.hbase.CellBuilderType;
 import org.apache.hadoop.hbase.HBaseClassTestRule;
@@ -135,10 +134,11 @@ public class TestAsyncTableRpcPriority {
           case INCREMENT:
             ColumnValue value = req.getColumnValue(0);
             QualifierValue qvalue = value.getQualifierValue(0);
-            Cell cell = CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setType(Type.Put)
-              .setRow(req.getRow().toByteArray()).setFamily(value.getFamily().toByteArray())
-              .setQualifier(qvalue.getQualifier().toByteArray())
-              .setValue(qvalue.getValue().toByteArray()).build();
+            Cell cell =
+              CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setType(Cell.Type.Put)
+                .setRow(req.getRow().toByteArray()).setFamily(value.getFamily().toByteArray())
+                .setQualifier(qvalue.getQualifier().toByteArray())
+                .setValue(qvalue.getValue().toByteArray()).build();
             resp = MutateResponse.newBuilder()
               .setResult(ProtobufUtil.toResult(Result.create(Arrays.asList(cell)))).build();
             break;
@@ -496,8 +496,8 @@ public class TestAsyncTableRpcPriority {
             assertFalse("close scanner should not come in with scan priority " + scanPriority,
               req.hasCloseScanner() && req.getCloseScanner());
 
-            Cell cell = CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setType(Type.Put)
-              .setRow(Bytes.toBytes(scanNextCalled.incrementAndGet()))
+            Cell cell = CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY)
+              .setType(Cell.Type.Put).setRow(Bytes.toBytes(scanNextCalled.incrementAndGet()))
               .setFamily(Bytes.toBytes("cf")).setQualifier(Bytes.toBytes("cq"))
               .setValue(Bytes.toBytes("v")).build();
             Result result = Result.create(Arrays.asList(cell));
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableTracing.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableTracing.java
index a5ea94e7cae..3a8f1c55380 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableTracing.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableTracing.java
@@ -389,8 +389,8 @@ public class TestAsyncTableTracing {
   @Test
   public void testCheckAndMutateBuilderThenMutations() throws IOException {
     RowMutations mutations = new RowMutations(Bytes.toBytes(0))
-      .add((Mutation) (new Put(Bytes.toBytes(0)).addColumn(Bytes.toBytes("f"), Bytes.toBytes("cq"),
-        Bytes.toBytes("v"))))
+      .add((Mutation) new Put(Bytes.toBytes(0)).addColumn(Bytes.toBytes("f"), Bytes.toBytes("cq"),
+        Bytes.toBytes("v")))
       .add((Mutation) new Delete(Bytes.toBytes(0)));
     testCheckAndMutateBuilder(mutations);
   }
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientNoCluster.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientNoCluster.java
index e4ce5ca4a3a..77a3b838a9b 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientNoCluster.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientNoCluster.java
@@ -32,7 +32,6 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentSkipListMap;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 import org.apache.commons.lang3.NotImplementedException;
@@ -72,7 +71,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import org.apache.hbase.thirdparty.com.google.common.base.Stopwatch;
-import org.apache.hbase.thirdparty.com.google.common.util.concurrent.ThreadFactoryBuilder;
 import org.apache.hbase.thirdparty.com.google.protobuf.ByteString;
 import org.apache.hbase.thirdparty.com.google.protobuf.RpcController;
 import org.apache.hbase.thirdparty.com.google.protobuf.ServiceException;
@@ -177,9 +175,6 @@ public class TestClientNoCluster extends Configured implements Tool {
       // I expect this exception.
       LOG.info("Got expected exception", e);
       t = e;
-    } catch (RetriesExhaustedException e) {
-      // This is the old, unwanted behavior. If we get here FAIL!!!
-      fail();
     } finally {
       table.close();
     }
@@ -242,9 +237,6 @@ public class TestClientNoCluster extends Configured implements Tool {
       // I expect this exception.
       LOG.info("Got expected exception", e);
       t = e;
-    } catch (RetriesExhaustedException e) {
-      // This is the old, unwanted behavior. If we get here FAIL!!!
-      fail();
     } finally {
       table.close();
       connection.close();
@@ -830,14 +822,8 @@ public class TestClientNoCluster extends Configured implements Tool {
     getConf().setInt("hbase.test.multi.too.many", 10);
     final int clients = 2;
 
-    // Have them all share the same connection so they all share the same instance of
-    // ManyServersManyRegionsConnection so I can keep an eye on how many requests by server.
-    final ExecutorService pool =
-      Executors.newCachedThreadPool(new ThreadFactoryBuilder().setNameFormat("p-pool-%d")
-        .setUncaughtExceptionHandler(Threads.LOGGING_EXCEPTION_HANDLER).build());
-    // Executors.newFixedThreadPool(servers * 10, Threads.getNamedThreadFactory("p"));
     // Share a connection so I can keep counts in the 'server' on concurrency.
-    final Connection sharedConnection = ConnectionFactory.createConnection(getConf()/* , pool */);
+    final Connection sharedConnection = ConnectionFactory.createConnection(getConf());
     try {
       Thread[] ts = new Thread[clients];
       for (int j = 0; j < ts.length; j++) {
@@ -850,7 +836,7 @@ public class TestClientNoCluster extends Configured implements Tool {
             try {
               cycle(id, c, sharedConnection);
             } catch (IOException e) {
-              e.printStackTrace();
+              LOG.info("Exception in cycle " + id, e);
             }
           }
         };
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientScanner.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientScanner.java
index 38776e337fe..ffc9caa27d7 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientScanner.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientScanner.java
@@ -39,7 +39,6 @@ import org.apache.hadoop.hbase.CellScanner;
 import org.apache.hadoop.hbase.HBaseClassTestRule;
 import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.KeyValue;
-import org.apache.hadoop.hbase.KeyValue.Type;
 import org.apache.hadoop.hbase.RegionLocations;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.client.ScannerCallable.MoreResults;
@@ -139,8 +138,8 @@ public class TestClientScanner {
   @SuppressWarnings("unchecked")
   public void testNoResultsHint() throws IOException {
     final Result[] results = new Result[1];
-    KeyValue kv1 =
-      new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1, Type.Maximum);
+    KeyValue kv1 = new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
+      KeyValue.Type.Maximum);
     results[0] = Result.create(new Cell[] { kv1 });
 
     RpcRetryingCaller<Result[]> caller = Mockito.mock(RpcRetryingCaller.class);
@@ -200,8 +199,8 @@ public class TestClientScanner {
   @SuppressWarnings("unchecked")
   public void testSizeLimit() throws IOException {
     final Result[] results = new Result[1];
-    KeyValue kv1 =
-      new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1, Type.Maximum);
+    KeyValue kv1 = new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
+      KeyValue.Type.Maximum);
     results[0] = Result.create(new Cell[] { kv1 });
 
     RpcRetryingCaller<Result[]> caller = Mockito.mock(RpcRetryingCaller.class);
@@ -259,11 +258,11 @@ public class TestClientScanner {
   @SuppressWarnings("unchecked")
   public void testCacheLimit() throws IOException {
     KeyValue kv1 = new KeyValue(Bytes.toBytes("row1"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
-      Type.Maximum);
+      KeyValue.Type.Maximum);
     KeyValue kv2 = new KeyValue(Bytes.toBytes("row2"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
-      Type.Maximum);
+      KeyValue.Type.Maximum);
     KeyValue kv3 = new KeyValue(Bytes.toBytes("row3"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
-      Type.Maximum);
+      KeyValue.Type.Maximum);
     final Result[] results = new Result[] { Result.create(new Cell[] { kv1 }),
       Result.create(new Cell[] { kv2 }), Result.create(new Cell[] { kv3 }) };
 
@@ -336,8 +335,8 @@ public class TestClientScanner {
   @SuppressWarnings("unchecked")
   public void testNoMoreResults() throws IOException {
     final Result[] results = new Result[1];
-    KeyValue kv1 =
-      new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1, Type.Maximum);
+    KeyValue kv1 = new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
+      KeyValue.Type.Maximum);
     results[0] = Result.create(new Cell[] { kv1 });
 
     RpcRetryingCaller<Result[]> caller = Mockito.mock(RpcRetryingCaller.class);
@@ -395,13 +394,13 @@ public class TestClientScanner {
   @SuppressWarnings("unchecked")
   public void testMoreResults() throws IOException {
     final Result[] results1 = new Result[1];
-    KeyValue kv1 =
-      new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1, Type.Maximum);
+    KeyValue kv1 = new KeyValue(Bytes.toBytes("row"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
+      KeyValue.Type.Maximum);
     results1[0] = Result.create(new Cell[] { kv1 });
 
     final Result[] results2 = new Result[1];
     KeyValue kv2 = new KeyValue(Bytes.toBytes("row2"), Bytes.toBytes("cf"), Bytes.toBytes("cq"), 1,
-      Type.Maximum);
+      KeyValue.Type.Maximum);
     results2[0] = Result.create(new Cell[] { kv2 });
 
     RpcRetryingCaller<Result[]> caller = Mockito.mock(RpcRetryingCaller.class);
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestCoprocessorDescriptor.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestCoprocessorDescriptor.java
index f1a8e000136..a56c863ce61 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestCoprocessorDescriptor.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestCoprocessorDescriptor.java
@@ -33,8 +33,6 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
 import org.junit.rules.TestName;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 @Category({ MiscTests.class, SmallTests.class })
 public class TestCoprocessorDescriptor {
@@ -43,8 +41,6 @@ public class TestCoprocessorDescriptor {
   public static final HBaseClassTestRule CLASS_RULE =
     HBaseClassTestRule.forClass(TestCoprocessorDescriptor.class);
 
-  private static final Logger LOG = LoggerFactory.getLogger(TestCoprocessorDescriptor.class);
-
   @Rule
   public TestName name = new TestName();
 
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestGet.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestGet.java
index 95e05911008..a690be27acf 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestGet.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestGet.java
@@ -250,8 +250,7 @@ public class TestGet {
   public void testGetRowConstructor() {
     byte[] row1 = Bytes.toBytes("testRow");
     byte[] row2 = Bytes.toBytes("testtestRow");
-    ByteBuffer rowBuffer = ByteBuffer.allocate(16);
-    rowBuffer = ByteBuffer.wrap(row1);
+    ByteBuffer rowBuffer = ByteBuffer.wrap(row1);
     Get get1 = new Get(rowBuffer);
     Get get2 = new Get(row2, 4, 7);
     Assert.assertArrayEquals(get1.getRow(), get2.getRow());
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestImmutableHTableDescriptor.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestImmutableHTableDescriptor.java
index a121219443d..be0649f3751 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestImmutableHTableDescriptor.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestImmutableHTableDescriptor.java
@@ -97,6 +97,7 @@ public class TestImmutableHTableDescriptor {
       hcd.setBlocksize(10);
       fail("ImmutableHColumnDescriptor can't be modified!!!");
     } catch (UnsupportedOperationException e) {
+      // Expected
     }
   }
 
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestMutation.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestMutation.java
index dcb4d6eb88a..718ca05b92f 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestMutation.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestMutation.java
@@ -23,7 +23,6 @@ import static org.junit.Assert.assertTrue;
 import java.io.IOException;
 import java.util.List;
 import org.apache.hadoop.hbase.Cell;
-import org.apache.hadoop.hbase.Cell.Type;
 import org.apache.hadoop.hbase.CellBuilderFactory;
 import org.apache.hadoop.hbase.CellBuilderType;
 import org.apache.hadoop.hbase.CellUtil;
@@ -51,7 +50,7 @@ public class TestMutation {
     byte[] family = Bytes.toBytes("CF-01");
 
     origin.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(origin.getRow())
-      .setFamily(family).setQualifier(Bytes.toBytes("q")).setType(Type.Put)
+      .setFamily(family).setQualifier(Bytes.toBytes("q")).setType(Cell.Type.Put)
       .setValue(Bytes.toBytes(100)).build());
     origin.addColumn(family, Bytes.toBytes("q0"), Bytes.toBytes("value"));
     origin.setTimeRange(100, 1000);
@@ -89,7 +88,7 @@ public class TestMutation {
     byte[] family = Bytes.toBytes("CF-01");
 
     origin.add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(origin.getRow())
-      .setFamily(family).setQualifier(Bytes.toBytes("q")).setType(Type.Delete).build());
+      .setFamily(family).setQualifier(Bytes.toBytes("q")).setType(Cell.Type.Delete).build());
     origin.addColumn(family, Bytes.toBytes("q0"));
     origin.addColumns(family, Bytes.toBytes("q1"));
     origin.addFamily(family);
@@ -187,10 +186,11 @@ public class TestMutation {
     Put put = new Put(row, true);
     put
       .add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(row).setFamily(family)
-        .setQualifier(qualifier0).setTimestamp(put.getTimestamp()).setType(Type.Put)
+        .setQualifier(qualifier0).setTimestamp(put.getTimestamp()).setType(Cell.Type.Put)
         .setValue(value0).build())
       .add(CellBuilderFactory.create(CellBuilderType.SHALLOW_COPY).setRow(row).setFamily(family)
-        .setQualifier(qualifier1).setTimestamp(ts1).setType(Type.Put).setValue(value1).build());
+        .setQualifier(qualifier1).setTimestamp(ts1).setType(Cell.Type.Put).setValue(value1)
+        .build());
 
     // Verify the cell of family:qualifier0
     Cell cell0 = put.get(family, qualifier0).get(0);
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestRegionInfoDisplay.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestRegionInfoDisplay.java
index 922b5fdce99..678eb28ce2e 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestRegionInfoDisplay.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestRegionInfoDisplay.java
@@ -88,8 +88,8 @@ public class TestRegionInfoDisplay {
     String firstPartOrig = origDesc.substring(0, origDesc.indexOf(Bytes.toStringBinary(startKey)));
     String secondPartOrig = origDesc.substring(
       origDesc.indexOf(Bytes.toStringBinary(startKey)) + Bytes.toStringBinary(startKey).length());
-    assert (firstPart.equals(firstPartOrig));
-    assert (secondPart.equals(secondPartOrig));
+    Assert.assertTrue(firstPart.equals(firstPartOrig));
+    Assert.assertTrue(secondPart.equals(secondPartOrig));
   }
 
   private void checkEquality(RegionInfo ri, Configuration conf) throws IOException {
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestScan.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestScan.java
index 8fe447e7fbd..66e83959718 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestScan.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestScan.java
@@ -165,22 +165,17 @@ public class TestScan {
   @Test
   public void testSetAuthorizations() {
     Scan scan = new Scan();
-    try {
-      scan.setAuthorizations(new Authorizations("\u002b|\u0029"));
-      scan.setAuthorizations(new Authorizations("A", "B", "0123", "A0", "1A1", "_a"));
-      scan.setAuthorizations(new Authorizations("A|B"));
-      scan.setAuthorizations(new Authorizations("A&B"));
-      scan.setAuthorizations(new Authorizations("!B"));
-      scan.setAuthorizations(new Authorizations("A", "(A)"));
-      scan.setAuthorizations(new Authorizations("A", "{A"));
-      scan.setAuthorizations(new Authorizations(" "));
-      scan.setAuthorizations(new Authorizations(":B"));
-      scan.setAuthorizations(new Authorizations("-B"));
-      scan.setAuthorizations(new Authorizations(".B"));
-      scan.setAuthorizations(new Authorizations("/B"));
-    } catch (IllegalArgumentException e) {
-      fail("should not throw exception");
-    }
+    scan.setAuthorizations(new Authorizations("A", "B", "0123", "A0", "1A1", "_a"));
+    scan.setAuthorizations(new Authorizations("A|B"));
+    scan.setAuthorizations(new Authorizations("A&B"));
+    scan.setAuthorizations(new Authorizations("!B"));
+    scan.setAuthorizations(new Authorizations("A", "(A)"));
+    scan.setAuthorizations(new Authorizations("A", "{A"));
+    scan.setAuthorizations(new Authorizations(" "));
+    scan.setAuthorizations(new Authorizations(":B"));
+    scan.setAuthorizations(new Authorizations("-B"));
+    scan.setAuthorizations(new Authorizations(".B"));
+    scan.setAuthorizations(new Authorizations("/B"));
   }
 
   @Test
@@ -193,8 +188,7 @@ public class TestScan {
       scan.setStartRow(new byte[HConstants.MAX_ROW_LENGTH + 1]);
       fail("should've thrown exception");
     } catch (IllegalArgumentException iae) {
-    } catch (Exception e) {
-      fail("expected IllegalArgumentException to be thrown");
+      // Expected
     }
 
     scan.setStopRow(null);
@@ -204,8 +198,7 @@ public class TestScan {
       scan.setStopRow(new byte[HConstants.MAX_ROW_LENGTH + 1]);
       fail("should've thrown exception");
     } catch (IllegalArgumentException iae) {
-    } catch (Exception e) {
-      fail("expected IllegalArgumentException to be thrown");
+      // Expected
     }
   }
 
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestSimpleRequestController.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestSimpleRequestController.java
index 36da042628a..6cb9960b96b 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestSimpleRequestController.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestSimpleRequestController.java
@@ -27,6 +27,7 @@ import java.io.InterruptedIOException;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.TreeMap;
 import java.util.concurrent.BrokenBarrierException;
 import java.util.concurrent.CyclicBarrier;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -100,9 +101,10 @@ public class TestSimpleRequestController {
     Configuration conf = HBaseConfiguration.create();
     conf.setLong(key, value);
     try {
-      SimpleRequestController controller = new SimpleRequestController(conf);
+      new SimpleRequestController(conf);
       fail("The " + key + " must be bigger than zero");
     } catch (IllegalArgumentException e) {
+      // Expected
     }
   }
 
@@ -122,7 +124,7 @@ public class TestSimpleRequestController {
     final int maxConcurrentTasksPerRegion = 1;
     final AtomicLong tasksInProgress = new AtomicLong(0);
     final Map<ServerName, AtomicInteger> taskCounterPerServer = new HashMap<>();
-    final Map<byte[], AtomicInteger> taskCounterPerRegion = new HashMap<>();
+    final Map<byte[], AtomicInteger> taskCounterPerRegion = new TreeMap<>(Bytes.BYTES_COMPARATOR);
     SimpleRequestController.TaskCountChecker countChecker =
       new SimpleRequestController.TaskCountChecker(maxTotalConcurrentTasks,
         maxConcurrentTasksPerServer, maxConcurrentTasksPerRegion, tasksInProgress,
@@ -285,7 +287,7 @@ public class TestSimpleRequestController {
     int maxConcurrentTasksPerRegion = 1;
     AtomicLong tasksInProgress = new AtomicLong(0);
     Map<ServerName, AtomicInteger> taskCounterPerServer = new HashMap<>();
-    Map<byte[], AtomicInteger> taskCounterPerRegion = new HashMap<>();
+    Map<byte[], AtomicInteger> taskCounterPerRegion = new TreeMap<>(Bytes.BYTES_COMPARATOR);
     SimpleRequestController.TaskCountChecker checker = new SimpleRequestController.TaskCountChecker(
       maxTotalConcurrentTasks, maxConcurrentTasksPerServer, maxConcurrentTasksPerRegion,
       tasksInProgress, taskCounterPerServer, taskCounterPerRegion);
@@ -359,10 +361,8 @@ public class TestSimpleRequestController {
       try {
         barrier.await();
         controller.waitForMaximumCurrentTasks(max.get(), 123, 1, null);
-      } catch (InterruptedIOException e) {
+      } catch (InterruptedIOException | InterruptedException | BrokenBarrierException e) {
         Assert.fail(e.getMessage());
-      } catch (InterruptedException | BrokenBarrierException e) {
-        e.printStackTrace();
       }
     };
     // First test that our runnable thread only exits when tasks is zero.
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestTableDescriptorBuilder.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestTableDescriptorBuilder.java
index 6aa4e6765e4..053b15d477c 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestTableDescriptorBuilder.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestTableDescriptorBuilder.java
@@ -59,8 +59,8 @@ public class TestTableDescriptorBuilder {
   @Test(expected = IOException.class)
   public void testAddCoprocessorTwice() throws IOException {
     String cpName = "a.b.c.d";
-    TableDescriptor htd = TableDescriptorBuilder.newBuilder(TableName.META_TABLE_NAME)
-      .setCoprocessor(cpName).setCoprocessor(cpName).build();
+    TableDescriptorBuilder.newBuilder(TableName.META_TABLE_NAME).setCoprocessor(cpName)
+      .setCoprocessor(cpName).build();
   }
 
   @Test
@@ -327,7 +327,7 @@ public class TestTableDescriptorBuilder {
   public void testModifyInexistentFamily() {
     byte[] familyName = Bytes.toBytes("cf");
     HColumnDescriptor hcd = new HColumnDescriptor(familyName);
-    TableDescriptor htd = TableDescriptorBuilder.newBuilder(TableName.valueOf(name.getMethodName()))
+    TableDescriptorBuilder.newBuilder(TableName.valueOf(name.getMethodName()))
       .modifyColumnFamily(hcd).build();
   }
 
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/filter/TestKeyOnlyFilter.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/filter/TestKeyOnlyFilter.java
index df17570a80a..f1f1e37ff52 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/filter/TestKeyOnlyFilter.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/filter/TestKeyOnlyFilter.java
@@ -27,7 +27,6 @@ import org.apache.hadoop.hbase.CellUtil;
 import org.apache.hadoop.hbase.HBaseClassTestRule;
 import org.apache.hadoop.hbase.HBaseCommonTestingUtility;
 import org.apache.hadoop.hbase.KeyValue;
-import org.apache.hadoop.hbase.KeyValue.Type;
 import org.apache.hadoop.hbase.KeyValueUtil;
 import org.apache.hadoop.hbase.filter.KeyOnlyFilter.KeyOnlyByteBufferExtendedCell;
 import org.apache.hadoop.hbase.filter.KeyOnlyFilter.KeyOnlyCell;
@@ -64,7 +63,8 @@ public class TestKeyOnlyFilter {
     byte[] q = Bytes.toBytes("qual1");
     byte[] v = Bytes.toBytes("val1");
     byte[] tags = Bytes.toBytes("tag1");
-    KeyValue kv = new KeyValue(r, f, q, 0, q.length, 1234L, Type.Put, v, 0, v.length, tags);
+    KeyValue kv =
+      new KeyValue(r, f, q, 0, q.length, 1234L, KeyValue.Type.Put, v, 0, v.length, tags);
 
     ByteBuffer buffer = ByteBuffer.wrap(kv.getBuffer());
     ByteBufferKeyValue bbCell = new ByteBufferKeyValue(buffer, 0, buffer.remaining());
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestCellBlockBuilder.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestCellBlockBuilder.java
index f9c93811b4e..fccea923635 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestCellBlockBuilder.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestCellBlockBuilder.java
@@ -154,7 +154,7 @@ public class TestCellBlockBuilder {
     StopWatch timer = new StopWatch();
     timer.start();
     for (int i = 0; i < cycles; i++) {
-      timerTest(builder, timer, count, size, codec, compressor, false);
+      timerTest(builder, count, size, codec, compressor, false);
     }
     timer.stop();
     LOG.info("Codec=" + codec + ", compression=" + compressor + ", sized=" + false + ", count="
@@ -162,16 +162,15 @@ public class TestCellBlockBuilder {
     timer.reset();
     timer.start();
     for (int i = 0; i < cycles; i++) {
-      timerTest(builder, timer, count, size, codec, compressor, true);
+      timerTest(builder, count, size, codec, compressor, true);
     }
     timer.stop();
     LOG.info("Codec=" + codec + ", compression=" + compressor + ", sized=" + true + ", count="
       + count + ", size=" + size + ", + took=" + timer.getTime() + "ms");
   }
 
-  private static void timerTest(final CellBlockBuilder builder, final StopWatch timer,
-    final int count, final int size, final Codec codec, final CompressionCodec compressor,
-    final boolean sized) throws IOException {
+  private static void timerTest(final CellBlockBuilder builder, final int count, final int size,
+    final Codec codec, final CompressionCodec compressor, final boolean sized) throws IOException {
     doBuildCellBlockUndoCellBlock(builder, codec, compressor, count, size, sized);
   }
 
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestNettyRpcConnection.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestNettyRpcConnection.java
index a9c40fd3bb7..73f3653a902 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestNettyRpcConnection.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/ipc/TestNettyRpcConnection.java
@@ -20,6 +20,7 @@ package org.apache.hadoop.hbase.ipc;
 import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 import java.io.IOException;
@@ -69,9 +70,8 @@ public class TestNettyRpcConnection {
 
   @Test
   public void testPrivateMethodExecutedInEventLoop() throws IllegalAccessException {
-    // make sure the test is executed with "-ea"
     assertThrows(AssertionError.class, () -> {
-      assert false;
+      assertTrue(false);
     });
     for (Method method : NettyRpcConnection.class.getDeclaredMethods()) {
       if (Modifier.isPrivate(method.getModifiers()) && !method.getName().contains("$")) {
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/quotas/TestQuotaGlobalsSettingsBypass.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/quotas/TestQuotaGlobalsSettingsBypass.java
index e2843180938..a3c96eb45aa 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/quotas/TestQuotaGlobalsSettingsBypass.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/quotas/TestQuotaGlobalsSettingsBypass.java
@@ -143,6 +143,7 @@ public class TestQuotaGlobalsSettingsBypass {
       one.merge(two);
       fail("Expected to see an Exception merging " + two + " into " + one);
     } catch (IllegalArgumentException e) {
+      // Expected
     }
   }
 }
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/security/TestHBaseSaslRpcClient.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/security/TestHBaseSaslRpcClient.java
index 60bd80fb58f..7b42ba224fa 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/security/TestHBaseSaslRpcClient.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/security/TestHBaseSaslRpcClient.java
@@ -138,14 +138,8 @@ public class TestHBaseSaslRpcClient {
   @Test
   public void testHBaseSaslRpcClientCreation() throws Exception {
     // creation kerberos principal check section
-    assertFalse(assertSuccessCreationKerberosPrincipal(null));
-    assertFalse(assertSuccessCreationKerberosPrincipal("DOMAIN.COM"));
-    assertFalse(assertSuccessCreationKerberosPrincipal("principal/DOMAIN.COM"));
-    if (!assertSuccessCreationKerberosPrincipal("principal/localhost@DOMAIN.COM")) {
-      // XXX: This can fail if kerberos support in the OS is not sane, see HBASE-10107.
-      // For now, don't assert, just warn
-      LOG.warn("Could not create a SASL client with valid Kerberos credential");
-    }
+    // Note this is mocked in a way that doesn't care about principal names
+    assertFalse(assertSuccessCreationKerberos());
 
     // creation digest principal check section
     assertFalse(assertSuccessCreationDigestPrincipal(null, null));
@@ -155,9 +149,8 @@ public class TestHBaseSaslRpcClient {
     assertTrue(assertSuccessCreationDigestPrincipal(DEFAULT_USER_NAME, DEFAULT_USER_PASSWORD));
 
     // creation simple principal check section
-    assertFalse(assertSuccessCreationSimplePrincipal("", ""));
-    assertFalse(assertSuccessCreationSimplePrincipal(null, null));
-    assertFalse(assertSuccessCreationSimplePrincipal(DEFAULT_USER_NAME, DEFAULT_USER_PASSWORD));
+    // Note this is mocked in a way that doesn't care about principal names
+    assertFalse(assertSuccessCreationSimple());
 
     // exceptions check section
     assertTrue(assertIOExceptionThenSaslClientIsNull(DEFAULT_USER_NAME, DEFAULT_USER_PASSWORD));
@@ -245,10 +238,11 @@ public class TestHBaseSaslRpcClient {
     }
   }
 
-  private boolean assertSuccessCreationKerberosPrincipal(String principal) {
+  private boolean assertSuccessCreationKerberos() {
     HBaseSaslRpcClient rpcClient = null;
     try {
-      rpcClient = createSaslRpcClientForKerberos(principal);
+      // createSaslRpcClientForKerberos is mocked in a way that doesn't care about principal names
+      rpcClient = createSaslRpcClientForKerberos();
     } catch (Exception ex) {
       LOG.error(ex.getMessage(), ex);
     }
@@ -268,17 +262,17 @@ public class TestHBaseSaslRpcClient {
     return rpcClient != null;
   }
 
-  private boolean assertSuccessCreationSimplePrincipal(String principal, String password) {
+  private boolean assertSuccessCreationSimple() {
     HBaseSaslRpcClient rpcClient = null;
     try {
-      rpcClient = createSaslRpcClientSimple(principal, password);
+      rpcClient = createSaslRpcClientSimple();
     } catch (Exception ex) {
       LOG.error(ex.getMessage(), ex);
     }
     return rpcClient != null;
   }
 
-  private HBaseSaslRpcClient createSaslRpcClientForKerberos(String principal) throws IOException {
+  private HBaseSaslRpcClient createSaslRpcClientForKerberos() throws IOException {
     return new HBaseSaslRpcClient(HBaseConfiguration.create(),
       new GssSaslClientAuthenticationProvider(), createTokenMock(), Mockito.mock(InetAddress.class),
       Mockito.mock(SecurityInfo.class), false);
@@ -294,8 +288,7 @@ public class TestHBaseSaslRpcClient {
     return token;
   }
 
-  private HBaseSaslRpcClient createSaslRpcClientSimple(String principal, String password)
-    throws IOException {
+  private HBaseSaslRpcClient createSaslRpcClientSimple() throws IOException {
     return new HBaseSaslRpcClient(HBaseConfiguration.create(),
       new SimpleSaslClientAuthenticationProvider(), createTokenMock(),
       Mockito.mock(InetAddress.class), Mockito.mock(SecurityInfo.class), false);
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestRoundRobinPoolMap.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestRoundRobinPoolMap.java
index d7ce6265b8c..04ba2570eac 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestRoundRobinPoolMap.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestRoundRobinPoolMap.java
@@ -120,10 +120,10 @@ public class TestRoundRobinPoolMap extends PoolMapTestBase {
           String value = Integer.toString(id.getAndIncrement());
           String result = poolMap.getOrCreate(key, () -> value);
           results.add(result);
-
-          Thread.yield();
+          // Sleep for a short time to ensure a yield. Thread#yield has platform dependent behavior.
+          Thread.sleep(10);
         }
-      } catch (IOException e) {
+      } catch (Exception e) {
         throw new CompletionException(e);
       }
     };
diff --git a/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestThreadLocalPoolMap.java b/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestThreadLocalPoolMap.java
index 45f533f1a73..d83944ef7f3 100644
--- a/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestThreadLocalPoolMap.java
+++ b/hbase-client/src/test/java/org/apache/hadoop/hbase/util/TestThreadLocalPoolMap.java
@@ -95,10 +95,10 @@ public class TestThreadLocalPoolMap extends PoolMapTestBase {
         for (int i = 0; i < 3; i++) {
           String result = poolMap.getOrCreate(key, () -> myId);
           assertEquals(myId, result);
-
-          Thread.yield();
+          // Sleep for a short period of time to yield. Thread#yield is platform dependent.
+          Thread.sleep(10);
         }
-      } catch (IOException e) {
+      } catch (Exception e) {
         throw new CompletionException(e);
       }
     };