diff --git a/client/rest-high-level/src/main/java/org/elasticsearch/client/RequestConverters.java b/client/rest-high-level/src/main/java/org/elasticsearch/client/RequestConverters.java
index 17b7055a522..293a9623c53 100644
--- a/client/rest-high-level/src/main/java/org/elasticsearch/client/RequestConverters.java
+++ b/client/rest-high-level/src/main/java/org/elasticsearch/client/RequestConverters.java
@@ -64,6 +64,7 @@ import org.elasticsearch.common.SuppressForbidden;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.lucene.uid.Versions;
 import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.DeprecationHandler;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
 import org.elasticsearch.common.xcontent.ToXContent;
@@ -855,10 +856,10 @@ final class RequestConverters {
                 if (fetchSourceContext.fetchSource() == false) {
                     putParam("_source", Boolean.FALSE.toString());
                 }
-                if (fetchSourceContext.includes() != null && fetchSourceContext.includes().length > 0) {
+                if (CollectionUtils.isEmpty(fetchSourceContext.includes()) == false) {
                     putParam("_source_includes", String.join(",", fetchSourceContext.includes()));
                 }
-                if (fetchSourceContext.excludes() != null && fetchSourceContext.excludes().length > 0) {
+                if (CollectionUtils.isEmpty(fetchSourceContext.excludes()) == false) {
                     putParam("_source_excludes", String.join(",", fetchSourceContext.excludes()));
                 }
             }
@@ -866,7 +867,7 @@ final class RequestConverters {
         }
 
         Params withFields(String[] fields) {
-            if (fields != null && fields.length > 0) {
+            if (CollectionUtils.isEmpty(fields) == false) {
                 return putParam("fields", String.join(",", fields));
             }
             return this;
@@ -967,7 +968,7 @@ final class RequestConverters {
         }
 
         Params withStoredFields(String[] storedFields) {
-            if (storedFields != null && storedFields.length > 0) {
+            if (CollectionUtils.isEmpty(storedFields) == false) {
                 return putParam("stored_fields", String.join(",", storedFields));
             }
             return this;
diff --git a/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterRequestConvertersTests.java b/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterRequestConvertersTests.java
index 59bf52a6773..460fbece1de 100644
--- a/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterRequestConvertersTests.java
+++ b/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterRequestConvertersTests.java
@@ -29,6 +29,7 @@ import org.elasticsearch.action.support.master.AcknowledgedRequest;
 import org.elasticsearch.client.cluster.RemoteInfoRequest;
 import org.elasticsearch.cluster.health.ClusterHealthStatus;
 import org.elasticsearch.common.Priority;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.test.ESTestCase;
 import org.hamcrest.CoreMatchers;
 import org.junit.Assert;
@@ -142,7 +143,7 @@ public class ClusterRequestConvertersTests extends ESTestCase {
         Assert.assertThat(request, CoreMatchers.notNullValue());
         Assert.assertThat(request.getMethod(), equalTo(HttpGet.METHOD_NAME));
         Assert.assertThat(request.getEntity(), nullValue());
-        if (indices != null && indices.length > 0) {
+        if (CollectionUtils.isEmpty(indices) == false) {
             Assert.assertThat(request.getEndpoint(), equalTo("/_cluster/health/" + String.join(",", indices)));
         } else {
             Assert.assertThat(request.getEndpoint(), equalTo("/_cluster/health"));
diff --git a/client/rest-high-level/src/test/java/org/elasticsearch/client/IndicesRequestConvertersTests.java b/client/rest-high-level/src/test/java/org/elasticsearch/client/IndicesRequestConvertersTests.java
index c17c5fc3990..f129a5a19ff 100644
--- a/client/rest-high-level/src/test/java/org/elasticsearch/client/IndicesRequestConvertersTests.java
+++ b/client/rest-high-level/src/test/java/org/elasticsearch/client/IndicesRequestConvertersTests.java
@@ -474,7 +474,7 @@ public class IndicesRequestConvertersTests extends ESTestCase {
         }
 
         StringJoiner endpoint = new StringJoiner("/", "/", "");
-        if (indicesUnderTest != null && indicesUnderTest.length > 0) {
+        if (CollectionUtils.isEmpty(indicesUnderTest) == false) {
             endpoint.add(String.join(",", indicesUnderTest));
         }
         endpoint.add("_settings");
@@ -487,7 +487,7 @@ public class IndicesRequestConvertersTests extends ESTestCase {
                 }
             }
             getSettingsRequest.names(names);
-            if (names != null && names.length > 0) {
+            if (CollectionUtils.isEmpty(names) == false) {
                 endpoint.add(String.join(",", names));
             }
         }
@@ -1207,7 +1207,7 @@ public class IndicesRequestConvertersTests extends ESTestCase {
     public void testReloadAnalyzers() {
         String[] indices = RequestConvertersTests.randomIndicesNames(1, 5);
         StringJoiner endpoint = new StringJoiner("/", "/", "");
-        if (indices != null && indices.length > 0) {
+        if (CollectionUtils.isEmpty(indices) == false) {
             endpoint.add(String.join(",", indices));
         }
         ReloadAnalyzersRequest reloadRequest = new ReloadAnalyzersRequest(indices);
diff --git a/server/src/internalClusterTest/java/org/elasticsearch/recovery/RecoveryWhileUnderLoadIT.java b/server/src/internalClusterTest/java/org/elasticsearch/recovery/RecoveryWhileUnderLoadIT.java
index 2563eebd4a2..d673c26387c 100644
--- a/server/src/internalClusterTest/java/org/elasticsearch/recovery/RecoveryWhileUnderLoadIT.java
+++ b/server/src/internalClusterTest/java/org/elasticsearch/recovery/RecoveryWhileUnderLoadIT.java
@@ -33,6 +33,7 @@ import org.elasticsearch.common.Priority;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.index.IndexService;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.shard.DocsStats;
@@ -393,7 +394,7 @@ public class RecoveryWhileUnderLoadIT extends ESIntegTestCase {
         logger.info("iteration [{}] - successful shards: {} (expected {})", iteration,
                 searchResponse.getSuccessfulShards(), numberOfShards);
         logger.info("iteration [{}] - failed shards: {} (expected 0)", iteration, searchResponse.getFailedShards());
-        if (searchResponse.getShardFailures() != null && searchResponse.getShardFailures().length > 0) {
+        if (CollectionUtils.isEmpty(searchResponse.getShardFailures()) == false) {
             logger.info("iteration [{}] - shard failures: {}", iteration, Arrays.toString(searchResponse.getShardFailures()));
         }
         logger.info("iteration [{}] - returned documents: {} (expected {})", iteration,
diff --git a/server/src/main/java/org/apache/lucene/search/grouping/CollapseTopFieldDocs.java b/server/src/main/java/org/apache/lucene/search/grouping/CollapseTopFieldDocs.java
index 4dba67abdeb..9c0e6dfba91 100644
--- a/server/src/main/java/org/apache/lucene/search/grouping/CollapseTopFieldDocs.java
+++ b/server/src/main/java/org/apache/lucene/search/grouping/CollapseTopFieldDocs.java
@@ -26,6 +26,7 @@ import org.apache.lucene.search.SortField;
 import org.apache.lucene.search.TopFieldDocs;
 import org.apache.lucene.search.TotalHits;
 import org.apache.lucene.util.PriorityQueue;
+import org.elasticsearch.common.util.CollectionUtils;
 
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -184,7 +185,7 @@ public final class CollapseTopFieldDocs extends TopFieldDocs {
             if (shard.totalHits.relation == TotalHits.Relation.GREATER_THAN_OR_EQUAL_TO) {
                 totalHitsRelation = TotalHits.Relation.GREATER_THAN_OR_EQUAL_TO;
             }
-            if (shard.scoreDocs != null && shard.scoreDocs.length > 0) {
+            if (CollectionUtils.isEmpty(shard.scoreDocs) == false) {
                 availHitCount += shard.scoreDocs.length;
                 queue.add(new ShardRef(shardIDX, setShardIndex == false));
             }
diff --git a/server/src/main/java/org/elasticsearch/action/admin/cluster/health/TransportClusterHealthAction.java b/server/src/main/java/org/elasticsearch/action/admin/cluster/health/TransportClusterHealthAction.java
index a93aa554647..e3102b14207 100644
--- a/server/src/main/java/org/elasticsearch/action/admin/cluster/health/TransportClusterHealthAction.java
+++ b/server/src/main/java/org/elasticsearch/action/admin/cluster/health/TransportClusterHealthAction.java
@@ -42,6 +42,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.index.IndexNotFoundException;
 import org.elasticsearch.tasks.Task;
 import org.elasticsearch.threadpool.ThreadPool;
@@ -228,7 +229,7 @@ public class TransportClusterHealthAction extends TransportMasterNodeReadAction<
         if (request.waitForNodes().isEmpty() == false) {
             waitCount++;
         }
-        if (request.indices() != null && request.indices().length > 0) { // check that they actually exists in the meta data
+        if (CollectionUtils.isEmpty(request.indices()) == false) { // check that they actually exists in the meta data
             waitCount++;
         }
         return waitCount;
@@ -282,7 +283,7 @@ public class TransportClusterHealthAction extends TransportMasterNodeReadAction<
                 waitForCounter++;
             }
         }
-        if (request.indices() != null && request.indices().length > 0) {
+        if (CollectionUtils.isEmpty(request.indices()) == false) {
             try {
                 indexNameExpressionResolver.concreteIndexNames(clusterState, IndicesOptions.strictExpand(), true, request.indices());
                 waitForCounter++;
diff --git a/server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/status/TransportSnapshotsStatusAction.java b/server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/status/TransportSnapshotsStatusAction.java
index b7c59e8f210..2d2c8ace15f 100644
--- a/server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/status/TransportSnapshotsStatusAction.java
+++ b/server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/status/TransportSnapshotsStatusAction.java
@@ -39,6 +39,7 @@ import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.util.set.Sets;
 import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.index.snapshots.IndexShardSnapshotStatus;
@@ -208,7 +209,7 @@ public class TransportSnapshotsStatusAction extends TransportMasterNodeAction<Sn
         }
         // Now add snapshots on disk that are not currently running
         final String repositoryName = request.repository();
-        if (Strings.hasText(repositoryName) && request.snapshots() != null && request.snapshots().length > 0) {
+        if (Strings.hasText(repositoryName) && CollectionUtils.isEmpty(request.snapshots()) == false) {
             loadRepositoryData(snapshotsInProgress, request, builder, currentSnapshotNames, repositoryName, listener);
         } else {
             listener.onResponse(new SnapshotsStatusResponse(Collections.unmodifiableList(builder)));
diff --git a/server/src/main/java/org/elasticsearch/action/admin/indices/close/CloseIndexResponse.java b/server/src/main/java/org/elasticsearch/action/admin/indices/close/CloseIndexResponse.java
index 82b956fa711..b25e7c09452 100644
--- a/server/src/main/java/org/elasticsearch/action/admin/indices/close/CloseIndexResponse.java
+++ b/server/src/main/java/org/elasticsearch/action/admin/indices/close/CloseIndexResponse.java
@@ -27,6 +27,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.Index;
@@ -203,7 +204,7 @@ public class CloseIndexResponse extends ShardsAcknowledgedResponse {
         }
 
         public boolean hasFailures() {
-            return failures != null && failures.length > 0;
+            return CollectionUtils.isEmpty(failures) == false;
         }
 
         public int getId() {
diff --git a/server/src/main/java/org/elasticsearch/action/admin/indices/mapping/put/PutMappingRequest.java b/server/src/main/java/org/elasticsearch/action/admin/indices/mapping/put/PutMappingRequest.java
index 9bccfa9001b..9a876ecfa2b 100644
--- a/server/src/main/java/org/elasticsearch/action/admin/indices/mapping/put/PutMappingRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/admin/indices/mapping/put/PutMappingRequest.java
@@ -33,6 +33,7 @@ import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentHelper;
@@ -118,7 +119,7 @@ public class PutMappingRequest extends AcknowledgedRequest<PutMappingRequest> im
         } else if (source.isEmpty()) {
             validationException = addValidationError("mapping source is empty", validationException);
         }
-        if (concreteIndex != null && (indices != null && indices.length > 0)) {
+        if (concreteIndex != null && CollectionUtils.isEmpty(indices) == false) {
             validationException = addValidationError("either concrete index or unresolved indices can be set, concrete index: ["
                 + concreteIndex + "] and indices: " + Arrays.asList(indices) , validationException);
         }
diff --git a/server/src/main/java/org/elasticsearch/action/search/SearchPhaseExecutionException.java b/server/src/main/java/org/elasticsearch/action/search/SearchPhaseExecutionException.java
index 8b4187c7cf0..aad3e01e35e 100644
--- a/server/src/main/java/org/elasticsearch/action/search/SearchPhaseExecutionException.java
+++ b/server/src/main/java/org/elasticsearch/action/search/SearchPhaseExecutionException.java
@@ -24,6 +24,7 @@ import org.elasticsearch.ExceptionsHelper;
 import org.elasticsearch.action.ShardOperationFailedException;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.rest.RestStatus;
 
@@ -119,7 +120,7 @@ public class SearchPhaseExecutionException extends ElasticsearchException {
     private static String buildMessage(String phaseName, String msg, ShardSearchFailure[] shardFailures) {
         StringBuilder sb = new StringBuilder();
         sb.append("Failed to execute phase [").append(phaseName).append("], ").append(msg);
-        if (shardFailures != null && shardFailures.length > 0) {
+        if (CollectionUtils.isEmpty(shardFailures) == false) {
             sb.append("; shardFailures ");
             for (ShardSearchFailure shardFailure : shardFailures) {
                 if (shardFailure.shard() != null) {
diff --git a/server/src/main/java/org/elasticsearch/action/support/tasks/BaseTasksRequest.java b/server/src/main/java/org/elasticsearch/action/support/tasks/BaseTasksRequest.java
index f44434192d7..b4b7ee5ac68 100644
--- a/server/src/main/java/org/elasticsearch/action/support/tasks/BaseTasksRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/support/tasks/BaseTasksRequest.java
@@ -26,6 +26,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.tasks.Task;
 import org.elasticsearch.tasks.TaskId;
 
@@ -159,7 +160,7 @@ public class BaseTasksRequest<Request extends BaseTasksRequest<Request>> extends
     }
 
     public boolean match(Task task) {
-        if (getActions() != null && getActions().length > 0 && Regex.simpleMatch(getActions(), task.getAction()) == false) {
+        if (CollectionUtils.isEmpty(getActions()) == false && Regex.simpleMatch(getActions(), task.getAction()) == false) {
             return false;
         }
         if (getTaskId().isSet()) {
diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolver.java b/server/src/main/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolver.java
index 2c50f0383de..cc5669cb394 100644
--- a/server/src/main/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolver.java
+++ b/server/src/main/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolver.java
@@ -31,6 +31,7 @@ import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.time.DateFormatter;
 import org.elasticsearch.common.time.DateMathParser;
 import org.elasticsearch.common.time.DateUtils;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.util.set.Sets;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.index.IndexNotFoundException;
@@ -311,7 +312,7 @@ public class IndexNameExpressionResolver {
      * @return the concrete index obtained as a result of the index resolution
      */
     public Index concreteSingleIndex(ClusterState state, IndicesRequest request) {
-        String indexExpression = request.indices() != null && request.indices().length > 0 ? request.indices()[0] : null;
+        String indexExpression = CollectionUtils.isEmpty(request.indices()) ? null : request.indices()[0];
         Index[] indices = concreteIndices(state, request.indicesOptions(), indexExpression);
         if (indices.length != 1) {
             throw new IllegalArgumentException("unable to return a single index as the index and options" +
diff --git a/server/src/main/java/org/elasticsearch/index/analysis/CustomAnalyzer.java b/server/src/main/java/org/elasticsearch/index/analysis/CustomAnalyzer.java
index 66ffc33a3c9..98c0c7f28fb 100644
--- a/server/src/main/java/org/elasticsearch/index/analysis/CustomAnalyzer.java
+++ b/server/src/main/java/org/elasticsearch/index/analysis/CustomAnalyzer.java
@@ -22,6 +22,7 @@ package org.elasticsearch.index.analysis;
 import org.apache.lucene.analysis.Analyzer;
 import org.apache.lucene.analysis.TokenStream;
 import org.apache.lucene.analysis.Tokenizer;
+import org.elasticsearch.common.util.CollectionUtils;
 
 import java.io.Reader;
 
@@ -97,7 +98,7 @@ public final class CustomAnalyzer extends Analyzer implements AnalyzerComponents
     @Override
     protected Reader initReader(String fieldName, Reader reader) {
         CharFilterFactory[] charFilters = charFilters();
-        if (charFilters != null && charFilters.length > 0) {
+        if (CollectionUtils.isEmpty(charFilters) == false) {
             for (CharFilterFactory charFilter : charFilters) {
                 reader = charFilter.create(reader);
             }
diff --git a/server/src/main/java/org/elasticsearch/index/analysis/ReloadableCustomAnalyzer.java b/server/src/main/java/org/elasticsearch/index/analysis/ReloadableCustomAnalyzer.java
index 7d3b8532cae..bfe155d5351 100644
--- a/server/src/main/java/org/elasticsearch/index/analysis/ReloadableCustomAnalyzer.java
+++ b/server/src/main/java/org/elasticsearch/index/analysis/ReloadableCustomAnalyzer.java
@@ -24,6 +24,7 @@ import org.apache.lucene.analysis.TokenStream;
 import org.apache.lucene.analysis.Tokenizer;
 import org.apache.lucene.util.CloseableThreadLocal;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.util.CollectionUtils;
 
 import java.io.Reader;
 import java.util.Map;
@@ -152,7 +153,7 @@ public final class ReloadableCustomAnalyzer extends Analyzer implements Analyzer
     @Override
     protected Reader initReader(String fieldName, Reader reader) {
         final AnalyzerComponents components = getStoredComponents();
-        if (components.getCharFilters() != null && components.getCharFilters().length > 0) {
+        if (CollectionUtils.isEmpty(components.getCharFilters()) == false) {
             for (CharFilterFactory charFilter : components.getCharFilters()) {
                 reader = charFilter.create(reader);
             }
diff --git a/server/src/main/java/org/elasticsearch/index/engine/CompletionStatsCache.java b/server/src/main/java/org/elasticsearch/index/engine/CompletionStatsCache.java
index b1dfd9d2189..759094736b7 100644
--- a/server/src/main/java/org/elasticsearch/index/engine/CompletionStatsCache.java
+++ b/server/src/main/java/org/elasticsearch/index/engine/CompletionStatsCache.java
@@ -31,6 +31,7 @@ import org.elasticsearch.action.support.PlainActionFuture;
 import org.elasticsearch.common.FieldMemoryStats;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.regex.Regex;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.search.suggest.completion.CompletionStats;
 
 import java.util.function.Supplier;
@@ -123,7 +124,7 @@ class CompletionStatsCache implements ReferenceManager.RefreshListener {
 
     private static CompletionStats filterCompletionStatsByFieldName(String[] fieldNamePatterns, CompletionStats fullCompletionStats) {
         final FieldMemoryStats fieldMemoryStats;
-        if (fieldNamePatterns != null && fieldNamePatterns.length > 0) {
+        if (CollectionUtils.isEmpty(fieldNamePatterns) == false) {
             final ObjectLongHashMap<String> completionFields = new ObjectLongHashMap<>(fieldNamePatterns.length);
             for (ObjectLongCursor<String> fieldCursor : fullCompletionStats.getFields()) {
                 if (Regex.simpleMatch(fieldNamePatterns, fieldCursor.key)) {
diff --git a/server/src/main/java/org/elasticsearch/index/fielddata/ShardFieldData.java b/server/src/main/java/org/elasticsearch/index/fielddata/ShardFieldData.java
index ed9dd14328d..3d79076dc3a 100644
--- a/server/src/main/java/org/elasticsearch/index/fielddata/ShardFieldData.java
+++ b/server/src/main/java/org/elasticsearch/index/fielddata/ShardFieldData.java
@@ -24,6 +24,7 @@ import org.apache.lucene.util.Accountable;
 import org.elasticsearch.common.FieldMemoryStats;
 import org.elasticsearch.common.metrics.CounterMetric;
 import org.elasticsearch.common.regex.Regex;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
 import org.elasticsearch.index.shard.ShardId;
 
@@ -38,7 +39,7 @@ public class ShardFieldData implements IndexFieldDataCache.Listener {
 
     public FieldDataStats stats(String... fields) {
         ObjectLongHashMap<String> fieldTotals = null;
-        if (fields != null && fields.length > 0) {
+        if (CollectionUtils.isEmpty(fields) == false) {
             fieldTotals = new ObjectLongHashMap<>();
             for (Map.Entry<String, CounterMetric> entry : perFieldTotals.entrySet()) {
                 if (Regex.simpleMatch(fields, entry.getKey())) {
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/SourceFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/SourceFieldMapper.java
index 2ac2d515276..fa7173c5d4e 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/SourceFieldMapper.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/SourceFieldMapper.java
@@ -31,6 +31,7 @@ import org.elasticsearch.common.collect.Tuple;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentHelper;
@@ -192,7 +193,7 @@ public class SourceFieldMapper extends MetadataFieldMapper {
         this.enabled = enabled;
         this.includes = includes;
         this.excludes = excludes;
-        final boolean filtered = (includes != null && includes.length > 0) || (excludes != null && excludes.length > 0);
+        final boolean filtered = CollectionUtils.isEmpty(includes) == false || CollectionUtils.isEmpty(excludes) == false;
         this.filter = enabled && filtered && fieldType().stored() ? XContentMapValues.filter(includes, excludes) : null;
         this.complete = enabled && includes == null && excludes == null;
     }
diff --git a/server/src/main/java/org/elasticsearch/index/query/SimpleQueryStringBuilder.java b/server/src/main/java/org/elasticsearch/index/query/SimpleQueryStringBuilder.java
index 1141dd95970..64a9fc6d57b 100644
--- a/server/src/main/java/org/elasticsearch/index/query/SimpleQueryStringBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/SimpleQueryStringBuilder.java
@@ -29,6 +29,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.lucene.search.Queries;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.search.QueryParserHelper;
@@ -273,7 +274,7 @@ public class SimpleQueryStringBuilder extends AbstractQueryBuilder<SimpleQuerySt
      * none are specified.
      */
     public SimpleQueryStringBuilder flags(SimpleQueryStringFlag... flags) {
-        if (flags != null && flags.length > 0) {
+        if (CollectionUtils.isEmpty(flags) == false) {
             int value = 0;
             for (SimpleQueryStringFlag flag : flags) {
                 value |= flag.value;
diff --git a/server/src/main/java/org/elasticsearch/index/search/stats/ShardSearchStats.java b/server/src/main/java/org/elasticsearch/index/search/stats/ShardSearchStats.java
index 0a19702e595..6e328f14451 100644
--- a/server/src/main/java/org/elasticsearch/index/search/stats/ShardSearchStats.java
+++ b/server/src/main/java/org/elasticsearch/index/search/stats/ShardSearchStats.java
@@ -23,6 +23,7 @@ import org.elasticsearch.common.collect.MapBuilder;
 import org.elasticsearch.common.metrics.CounterMetric;
 import org.elasticsearch.common.metrics.MeanMetric;
 import org.elasticsearch.common.regex.Regex;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.index.shard.SearchOperationListener;
 import org.elasticsearch.search.internal.SearchContext;
 
@@ -47,7 +48,7 @@ public final class ShardSearchStats implements SearchOperationListener {
     public SearchStats stats(String... groups) {
         SearchStats.Stats total = totalStats.stats();
         Map<String, SearchStats.Stats> groupsSt = null;
-        if (groups != null && groups.length > 0) {
+        if (CollectionUtils.isEmpty(groups) == false) {
             groupsSt = new HashMap<>(groupsStats.size());
             if (groups.length == 1 && groups[0].equals("_all")) {
                 for (Map.Entry<String, StatsHolder> entry : groupsStats.entrySet()) {
diff --git a/server/src/main/java/org/elasticsearch/rest/action/RestActions.java b/server/src/main/java/org/elasticsearch/rest/action/RestActions.java
index f6ad30706f7..0500d3594c5 100644
--- a/server/src/main/java/org/elasticsearch/rest/action/RestActions.java
+++ b/server/src/main/java/org/elasticsearch/rest/action/RestActions.java
@@ -28,6 +28,7 @@ import org.elasticsearch.action.support.nodes.BaseNodesResponse;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.lucene.uid.Versions;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.ToXContent.Params;
 import org.elasticsearch.common.xcontent.XContentBuilder;
@@ -88,7 +89,7 @@ public class RestActions {
             builder.field(SKIPPED_FIELD.getPreferredName(), skipped);
         }
         builder.field(FAILED_FIELD.getPreferredName(), failed);
-        if (shardFailures != null && shardFailures.length > 0) {
+        if (CollectionUtils.isEmpty(shardFailures) == false) {
             builder.startArray(FAILURES_FIELD.getPreferredName());
             for (ShardOperationFailedException shardFailure : ExceptionsHelper.groupBy(shardFailures)) {
                 shardFailure.toXContent(builder, params);
diff --git a/server/src/main/java/org/elasticsearch/search/SearchService.java b/server/src/main/java/org/elasticsearch/search/SearchService.java
index 03c4cd7e277..e61d5072790 100644
--- a/server/src/main/java/org/elasticsearch/search/SearchService.java
+++ b/server/src/main/java/org/elasticsearch/search/SearchService.java
@@ -45,6 +45,7 @@ import org.elasticsearch.common.settings.Setting.Property;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.util.BigArrays;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
 import org.elasticsearch.common.util.concurrent.ConcurrentMapLong;
 import org.elasticsearch.core.internal.io.IOUtils;
@@ -967,7 +968,7 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
         if (source.stats() != null) {
             context.groupStats(source.stats());
         }
-        if (source.searchAfter() != null && source.searchAfter().length > 0) {
+        if (CollectionUtils.isEmpty(source.searchAfter()) == false) {
             if (context.scrollContext() != null) {
                 throw new SearchException(shardTarget, "`search_after` cannot be used in a scroll context.");
             }
diff --git a/server/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/FastVectorHighlighter.java b/server/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/FastVectorHighlighter.java
index f011293c68d..ed2ddccc7ed 100644
--- a/server/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/FastVectorHighlighter.java
+++ b/server/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/FastVectorHighlighter.java
@@ -36,6 +36,7 @@ import org.apache.lucene.search.vectorhighlight.SingleFragListBuilder;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.text.Text;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.search.fetch.FetchPhaseExecutionException;
@@ -182,7 +183,7 @@ public class FastVectorHighlighter implements Highlighter {
                     entry.fragmentsBuilder, field.fieldOptions().preTags(), field.fieldOptions().postTags(), encoder);
             }
 
-            if (fragments != null && fragments.length > 0) {
+            if (CollectionUtils.isEmpty(fragments) == false) {
                 return new HighlightField(highlighterContext.fieldName, Text.convertFromStringArray(fragments));
             }
 
@@ -195,7 +196,7 @@ public class FastVectorHighlighter implements Highlighter {
                 fragments = entry.fragmentsBuilder.createFragments(hitContext.reader(), hitContext.docId(),
                     fieldType.name(), fieldFragList, 1, field.fieldOptions().preTags(),
                     field.fieldOptions().postTags(), encoder);
-                if (fragments != null && fragments.length > 0) {
+                if (CollectionUtils.isEmpty(fragments) == false) {
                     return new HighlightField(highlighterContext.fieldName, Text.convertFromStringArray(fragments));
                 }
             }
diff --git a/server/src/main/java/org/elasticsearch/watcher/FileWatcher.java b/server/src/main/java/org/elasticsearch/watcher/FileWatcher.java
index e75e73626c1..40f73a697e3 100644
--- a/server/src/main/java/org/elasticsearch/watcher/FileWatcher.java
+++ b/server/src/main/java/org/elasticsearch/watcher/FileWatcher.java
@@ -21,6 +21,7 @@ package org.elasticsearch.watcher;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.elasticsearch.common.io.FileSystemUtils;
+import org.elasticsearch.common.util.CollectionUtils;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -182,7 +183,7 @@ public class FileWatcher extends AbstractResourceWatcher<FileChangesListener> {
 
         private FileObserver[] listChildren(boolean initial) throws IOException {
             Path[] files = listFiles();
-            if (files != null && files.length > 0) {
+            if (CollectionUtils.isEmpty(files) == false) {
                 FileObserver[] children = new FileObserver[files.length];
                 for (int i = 0; i < files.length; i++) {
                     children[i] = createChild(files[i], initial);
@@ -195,7 +196,7 @@ public class FileWatcher extends AbstractResourceWatcher<FileChangesListener> {
 
         private void updateChildren() throws IOException {
             Path[] files = listFiles();
-            if (files != null && files.length > 0) {
+            if (CollectionUtils.isEmpty(files) == false) {
                 FileObserver[] newChildren = new FileObserver[files.length];
                 int child = 0;
                 int file = 0;
diff --git a/server/src/test/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilderTests.java b/server/src/test/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilderTests.java
index 9a43ca15fe6..029cd15747d 100644
--- a/server/src/test/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilderTests.java
+++ b/server/src/test/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilderTests.java
@@ -37,6 +37,7 @@ import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.lucene.search.MoreLikeThisQuery;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
@@ -161,7 +162,7 @@ public class MoreLikeThisQueryBuilderTests extends AbstractQueryTestCase<MoreLik
         } else {
             likeItems = randomLikeItems;
         }
-        if (randomBoolean() && likeItems != null && likeItems.length > 0) { // for the default field
+        if (randomBoolean() && CollectionUtils.isEmpty(likeItems) == false) { // for the default field
             queryBuilder = new MoreLikeThisQueryBuilder(null, likeItems);
         } else {
             queryBuilder = new MoreLikeThisQueryBuilder(randomFields, likeTexts, likeItems);
@@ -268,7 +269,7 @@ public class MoreLikeThisQueryBuilderTests extends AbstractQueryTestCase<MoreLik
 
     @Override
     protected void doAssertLuceneQuery(MoreLikeThisQueryBuilder queryBuilder, Query query, QueryShardContext context) throws IOException {
-        if (queryBuilder.likeItems() != null && queryBuilder.likeItems().length > 0) {
+        if (CollectionUtils.isEmpty(queryBuilder.likeItems()) == false) {
             assertThat(query, instanceOf(BooleanQuery.class));
             BooleanQuery booleanQuery = (BooleanQuery) query;
             for (BooleanClause booleanClause : booleanQuery) {
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java
index 543ab85a71b..08800d05269 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java
@@ -49,6 +49,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.common.xcontent.LoggingDeprecationHandler;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
@@ -511,7 +512,7 @@ public class JobResultsProvider {
                         SearchResponse searchResponse = itemResponse.getResponse();
                         ShardSearchFailure[] shardFailures = searchResponse.getShardFailures();
                         int unavailableShards = searchResponse.getTotalShards() - searchResponse.getSuccessfulShards();
-                        if (shardFailures != null && shardFailures.length > 0) {
+                        if (CollectionUtils.isEmpty(shardFailures) == false) {
                             LOGGER.error("[{}] Search request returned shard failures: {}", jobId, Arrays.toString(shardFailures));
                             listener.onFailure(
                                 new ElasticsearchException(ExceptionsHelper.shardFailuresToErrorMsg(jobId, shardFailures)));
@@ -617,7 +618,7 @@ public class JobResultsProvider {
                                 SearchResponse searchResponse = itemResponse.getResponse();
                                 ShardSearchFailure[] shardFailures = searchResponse.getShardFailures();
                                 int unavailableShards = searchResponse.getTotalShards() - searchResponse.getSuccessfulShards();
-                                if (shardFailures != null && shardFailures.length > 0) {
+                                if (CollectionUtils.isEmpty(shardFailures) == false) {
                                     LOGGER.error("[{}] Search request returned shard failures: {}", jobId,
                                         Arrays.toString(shardFailures));
                                     errorHandler.accept(new ElasticsearchException(