diff --git a/nifi-nar-bundles/nifi-atlas-bundle/nifi-atlas-reporting-task/src/main/java/org/apache/nifi/atlas/security/AtlasAuthN.java b/nifi-nar-bundles/nifi-atlas-bundle/nifi-atlas-reporting-task/src/main/java/org/apache/nifi/atlas/security/AtlasAuthN.java
index a0b036ec96..660c09b6e0 100644
--- a/nifi-nar-bundles/nifi-atlas-bundle/nifi-atlas-reporting-task/src/main/java/org/apache/nifi/atlas/security/AtlasAuthN.java
+++ b/nifi-nar-bundles/nifi-atlas-bundle/nifi-atlas-reporting-task/src/main/java/org/apache/nifi/atlas/security/AtlasAuthN.java
@@ -35,7 +35,7 @@ public interface AtlasAuthN {
      * Populate required Atlas application properties.
      * This method is called when Atlas reporting task generates atlas-application.properties.
      */
-    default void populateProperties(final Properties properties){};
+    default void populateProperties(final Properties properties){}
 
     default Optional<ValidationResult> validateRequiredField(ValidationContext context, PropertyDescriptor prop) {
         if (!context.getProperty(prop).isSet()) {
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-cluster/src/main/java/org/apache/nifi/cluster/coordination/http/replication/RequestReplicator.java b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-cluster/src/main/java/org/apache/nifi/cluster/coordination/http/replication/RequestReplicator.java
index 8a98ed7035..6af6111c2b 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-cluster/src/main/java/org/apache/nifi/cluster/coordination/http/replication/RequestReplicator.java
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-cluster/src/main/java/org/apache/nifi/cluster/coordination/http/replication/RequestReplicator.java
@@ -22,6 +22,8 @@ import java.util.Map;
 import java.util.Set;
 
 import org.apache.nifi.authorization.user.NiFiUser;
+import org.apache.nifi.cluster.manager.exception.ConnectingNodeMutableRequestException;
+import org.apache.nifi.cluster.manager.exception.DisconnectedNodeMutableRequestException;
 import org.apache.nifi.cluster.protocol.NodeIdentifier;
 
 public interface RequestReplicator {
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-core-api/src/main/java/org/apache/nifi/remote/protocol/ServerProtocol.java b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-core-api/src/main/java/org/apache/nifi/remote/protocol/ServerProtocol.java
index dede80f773..e5cece613a 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-core-api/src/main/java/org/apache/nifi/remote/protocol/ServerProtocol.java
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-core-api/src/main/java/org/apache/nifi/remote/protocol/ServerProtocol.java
@@ -74,7 +74,7 @@ public interface ServerProtocol extends VersionedRemoteResource {
      * @param peer peer
      * @return the codec to use
      * @throws IOException ioe
-     * @throws org.apache.nifi.remote.exception.ProtocolException pe
+     * @throws ProtocolException pe
      */
     FlowFileCodec negotiateCodec(Peer peer) throws IOException, ProtocolException;
 
@@ -90,7 +90,7 @@ public interface ServerProtocol extends VersionedRemoteResource {
      * @param peer peer
      * @return the RequestType that the peer would like to happen - or null, if
      * no data available
-     * @throws java.io.IOException ioe
+     * @throws IOException ioe
      */
     RequestType getRequestType(Peer peer) throws IOException;
 
@@ -103,8 +103,8 @@ public interface ServerProtocol extends VersionedRemoteResource {
      * @param codec codec
      *
      * @return the number of FlowFiles transferred
-     * @throws java.io.IOException ioe
-     * @throws org.apache.nifi.remote.exception.ProtocolException pe
+     * @throws IOException ioe
+     * @throws ProtocolException pe
      */
     int transferFlowFiles(Peer peer, ProcessContext context, ProcessSession session, FlowFileCodec codec) throws IOException, ProtocolException;
 
@@ -137,7 +137,7 @@ public interface ServerProtocol extends VersionedRemoteResource {
      * @param clusterNodeInfo the cluster information
      * @param self the node which received the request
      *
-     * @throws java.io.IOException ioe
+     * @throws IOException ioe
      */
     void sendPeerList(
             Peer peer,
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-api/src/main/java/org/apache/nifi/web/api/concurrent/RequestManager.java b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-api/src/main/java/org/apache/nifi/web/api/concurrent/RequestManager.java
index 580ab47148..f73ed0fb1c 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-api/src/main/java/org/apache/nifi/web/api/concurrent/RequestManager.java
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-api/src/main/java/org/apache/nifi/web/api/concurrent/RequestManager.java
@@ -20,6 +20,7 @@ package org.apache.nifi.web.api.concurrent;
 import java.util.function.Consumer;
 
 import org.apache.nifi.authorization.user.NiFiUser;
+import org.apache.nifi.web.ResourceNotFoundException;
 
 public interface RequestManager<T> {
 
diff --git a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-10-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-10-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
index 3cde7ce4d9..2708542179 100644
--- a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-10-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
+++ b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-10-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
@@ -270,7 +270,7 @@ final class KafkaProcessorUtils {
             final boolean knownValue = KafkaProcessorUtils.isStaticStringFieldNamePresent(subject, classType, CommonClientConfigs.class, SslConfigs.class, SaslConfigs.class);
             return new ValidationResult.Builder().subject(subject).explanation("Must be a known configuration parameter for this kafka client").valid(knownValue).build();
         }
-    };
+    }
 
     /**
      * Builds transit URI for provenance event. The transit URI will be in the
diff --git a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-11-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-11-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
index 9bc4917399..956b37de6b 100644
--- a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-11-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
+++ b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-11-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
@@ -272,7 +272,7 @@ final class KafkaProcessorUtils {
             final boolean knownValue = KafkaProcessorUtils.isStaticStringFieldNamePresent(subject, classType, CommonClientConfigs.class, SslConfigs.class, SaslConfigs.class);
             return new ValidationResult.Builder().subject(subject).explanation("Must be a known configuration parameter for this kafka client").valid(knownValue).build();
         }
-    };
+    }
 
     /**
      * Builds transit URI for provenance event. The transit URI will be in the
diff --git a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-9-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-9-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
index 5e9260aa41..2a662f228d 100644
--- a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-9-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
+++ b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-0-9-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
@@ -193,7 +193,7 @@ final class KafkaProcessorUtils {
             final boolean knownValue = KafkaProcessorUtils.isStaticStringFieldNamePresent(subject, classType, CommonClientConfigs.class, SslConfigs.class, SaslConfigs.class);
             return new ValidationResult.Builder().subject(subject).explanation("Must be a known configuration parameter for this kafka client").valid(knownValue).build();
         }
-    };
+    }
 
     /**
      * Builds transit URI for provenance event. The transit URI will be in the
diff --git a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-1-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-1-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
index 7c3c57896c..bec65d0d38 100644
--- a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-1-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
+++ b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-1-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
@@ -272,7 +272,7 @@ final class KafkaProcessorUtils {
             final boolean knownValue = KafkaProcessorUtils.isStaticStringFieldNamePresent(subject, classType, CommonClientConfigs.class, SslConfigs.class, SaslConfigs.class);
             return new ValidationResult.Builder().subject(subject).explanation("Must be a known configuration parameter for this kafka client").valid(knownValue).build();
         }
-    };
+    }
 
     /**
      * Builds transit URI for provenance event. The transit URI will be in the
diff --git a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-2-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-2-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
index 7c3c57896c..bec65d0d38 100644
--- a/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-2-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
+++ b/nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-2-0-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/KafkaProcessorUtils.java
@@ -272,7 +272,7 @@ final class KafkaProcessorUtils {
             final boolean knownValue = KafkaProcessorUtils.isStaticStringFieldNamePresent(subject, classType, CommonClientConfigs.class, SslConfigs.class, SaslConfigs.class);
             return new ValidationResult.Builder().subject(subject).explanation("Must be a known configuration parameter for this kafka client").valid(knownValue).build();
         }
-    };
+    }
 
     /**
      * Builds transit URI for provenance event. The transit URI will be in the
diff --git a/pom.xml b/pom.xml
index 1ce75b4ab2..30f0f7b4af 100644
--- a/pom.xml
+++ b/pom.xml
@@ -441,12 +441,12 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-checkstyle-plugin</artifactId>
-                    <version>2.17</version>
+                    <version>3.0.0</version>
                     <dependencies>
                         <dependency>
                             <groupId>com.puppycrawl.tools</groupId>
                             <artifactId>checkstyle</artifactId>
-                            <version>8.12</version>
+                            <version>8.21</version>
                         </dependency>
                     </dependencies>
                 </plugin>
@@ -539,6 +539,7 @@
                         <module name="Checker">
                             <property name="charset" value="UTF-8" />
                             <property name="severity" value="warning" />
+                            <property name="cacheFile" value="target/checkstyleCache"/>
                             <!-- Checks for whitespace -->
                             <!-- See http://checkstyle.sf.net/config_whitespace.html -->
                             <module name="FileTabCharacter">
@@ -568,7 +569,7 @@
                                 <module name="LeftCurly" />
                                 <module name="RightCurly" />
                                 <module name="RightCurly">
-                                    <property name="option" value="alone" />
+                                    <property name="option" value="alone_or_singleline" />
                                     <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT" />
                                 </module>
                                 <module name="SeparatorWrap">
@@ -599,6 +600,7 @@
                                 </module>
                                 <module name="NonEmptyAtclauseDescription" />
                                 <module name="JavadocMethod">
+                                    <property name="allowUndeclaredRTE" value="true" />
                                     <property name="allowMissingJavadoc" value="true" />
                                     <property name="allowMissingParamTags" value="true" />
                                     <property name="allowMissingThrowsTags" value="true" />