diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/OzoneConfiguration.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/OzoneConfiguration.java
index e324a63d3ba..b8742c6ba92 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/OzoneConfiguration.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/conf/OzoneConfiguration.java
@@ -30,6 +30,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.List;
@@ -163,15 +164,11 @@ public XMLConfiguration() {
     }
 
     public XMLConfiguration(List<Property> properties) {
-      this.properties = properties;
+      this.properties = new ArrayList<>(properties);
     }
 
     public List<Property> getProperties() {
-      return properties;
-    }
-
-    public void setProperties(List<Property> properties) {
-      this.properties = properties;
+      return Collections.unmodifiableList(properties);
     }
   }
 
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/freon/FakeClusterTopology.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/freon/FakeClusterTopology.java
index 2d29dc8565c..ba203f9c8e2 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/freon/FakeClusterTopology.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/freon/FakeClusterTopology.java
@@ -18,6 +18,7 @@
 package org.apache.hadoop.hdds.freon;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Random;
 import java.util.UUID;
@@ -36,40 +37,49 @@
  * Class to store pre-generated topology information for load-tests.
  */
 @SuppressWarnings("java:S2245") // no need for secure random
-public class FakeClusterTopology {
+public final class FakeClusterTopology {
 
   private static final Logger LOGGER =
       LoggerFactory.getLogger(FakeClusterTopology.class);
 
-  public static final FakeClusterTopology INSTANCE = new FakeClusterTopology();
+  public static final FakeClusterTopology INSTANCE = newFakeClusterTopology();
 
-  private List<DatanodeDetailsProto> datanodes = new ArrayList<>();
+  private final List<DatanodeDetailsProto> datanodes;
 
-  private List<Pipeline> pipelines = new ArrayList<>();
+  private final List<Pipeline> pipelines;
 
-  private Random random = new Random();
+  private final Random random = new Random();
 
-  public FakeClusterTopology() {
+  private static FakeClusterTopology newFakeClusterTopology() {
+    final int nodeCount = 9;
+    final List<DatanodeDetailsProto> datanodes = new ArrayList<>(nodeCount);
+    final List<Pipeline> pipelines = new ArrayList<>(nodeCount / 3);
     try {
-      for (int i = 0; i < 9; i++) {
+      for (int i = 0; i < nodeCount; i++) {
         datanodes.add(createDatanode());
         if ((i + 1) % 3 == 0) {
           pipelines.add(Pipeline.newBuilder()
               .setId(PipelineID.randomId().getProtobuf())
               .setFactor(ReplicationFactor.THREE)
               .setType(ReplicationType.RATIS)
-              .addMembers(getDatanode(i - 2))
-              .addMembers(getDatanode(i - 1))
-              .addMembers(getDatanode(i))
+              .addMembers(datanodes.get(i - 2))
+              .addMembers(datanodes.get(i - 1))
+              .addMembers(datanodes.get(i))
               .build());
         }
       }
     } catch (Exception ex) {
       LOGGER.error("Can't initialize FakeClusterTopology", ex);
     }
+    return new FakeClusterTopology(datanodes, pipelines);
   }
 
-  private DatanodeDetailsProto createDatanode() {
+  private FakeClusterTopology(List<DatanodeDetailsProto> datanodes, List<Pipeline> pipelines) {
+    this.datanodes = Collections.unmodifiableList(datanodes);
+    this.pipelines = Collections.unmodifiableList(pipelines);
+  }
+
+  private static DatanodeDetailsProto createDatanode() {
     return DatanodeDetailsProto.newBuilder()
         .setUuid(UUID.randomUUID().toString())
         .setHostName("localhost")
@@ -79,15 +89,11 @@ private DatanodeDetailsProto createDatanode() {
         .build();
   }
 
-  public DatanodeDetailsProto getDatanode(int i) {
-    return datanodes.get(i);
-  }
-
   public Pipeline getRandomPipeline() {
     return pipelines.get(random.nextInt(pipelines.size()));
   }
 
-  public List<DatanodeDetailsProto> getAllDatanodes() {
+  public Iterable<DatanodeDetailsProto> getAllDatanodes() {
     return datanodes;
   }
 }
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/protocol/DatanodeDetails.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/protocol/DatanodeDetails.java
index 224f961158f..f54b96eb049 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/protocol/DatanodeDetails.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/protocol/DatanodeDetails.java
@@ -242,7 +242,16 @@ public synchronized void setPort(Name name, int port) {
    * @return DataNode Ports
    */
   public synchronized List<Port> getPorts() {
-    return ports;
+    return new ArrayList<>(ports);
+  }
+
+  public synchronized boolean hasPort(int port) {
+    for (Port p : ports) {
+      if (p.getValue() == port) {
+        return true;
+      }
+    }
+    return false;
   }
 
   /**
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ScmInfo.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ScmInfo.java
index b9d823e8d81..19c39698dec 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ScmInfo.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ScmInfo.java
@@ -19,6 +19,7 @@
 package org.apache.hadoop.hdds.scm;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 /**
@@ -26,9 +27,9 @@
  * contains clusterId and the SCM Id.
  */
 public final class ScmInfo {
-  private String clusterId;
-  private String scmId;
-  private List<String> peerRoles;
+  private final String clusterId;
+  private final String scmId;
+  private final List<String> peerRoles;
 
   /**
    * Builder for ScmInfo.
@@ -36,7 +37,7 @@ public final class ScmInfo {
   public static class Builder {
     private String clusterId;
     private String scmId;
-    private List<String> peerRoles;
+    private final List<String> peerRoles;
 
     public Builder() {
       peerRoles = new ArrayList<>();
@@ -80,7 +81,7 @@ public ScmInfo build() {
   private ScmInfo(String clusterId, String scmId, List<String> peerRoles) {
     this.clusterId = clusterId;
     this.scmId = scmId;
-    this.peerRoles = peerRoles;
+    this.peerRoles = Collections.unmodifiableList(peerRoles);
   }
 
   /**
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/XceiverClientReply.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/XceiverClientReply.java
index b6834aba1eb..61fd0d8f033 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/XceiverClientReply.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/XceiverClientReply.java
@@ -22,6 +22,7 @@
 import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos
     .ContainerCommandResponseProto;
 
+import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
@@ -60,7 +61,7 @@ public void setLogIndex(long logIndex) {
   }
 
   public List<DatanodeDetails> getDatanodes() {
-    return datanodes;
+    return Collections.unmodifiableList(datanodes);
   }
 
   public void addDatanode(DatanodeDetails dn) {
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/container/common/helpers/ExcludeList.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/container/common/helpers/ExcludeList.java
index 2577a1e5ea2..258c0be8961 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/container/common/helpers/ExcludeList.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/container/common/helpers/ExcludeList.java
@@ -25,6 +25,7 @@
 import java.time.Clock;
 import java.time.ZoneOffset;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Map;
@@ -38,28 +39,24 @@
  */
 public class ExcludeList {
 
-  private final Map<DatanodeDetails, Long> datanodes;
-  private final Set<ContainerID> containerIds;
-  private final Set<PipelineID> pipelineIds;
+  private final Map<DatanodeDetails, Long> datanodes = new ConcurrentHashMap<>();
+  private final Set<ContainerID> containerIds = new HashSet<>();
+  private final Set<PipelineID> pipelineIds = new HashSet<>();
   private long expiryTime = 0;
-  private java.time.Clock clock;
+  private final Clock clock;
 
 
   public ExcludeList() {
-    datanodes = new ConcurrentHashMap<>();
-    containerIds = new HashSet<>();
-    pipelineIds = new HashSet<>();
     clock = Clock.system(ZoneOffset.UTC);
   }
 
-  public ExcludeList(long autoExpiryTime, java.time.Clock clock) {
-    this();
+  public ExcludeList(long autoExpiryTime, Clock clock) {
     this.expiryTime = autoExpiryTime;
     this.clock = clock;
   }
 
   public Set<ContainerID> getContainerIds() {
-    return containerIds;
+    return Collections.unmodifiableSet(containerIds);
   }
 
   public Set<DatanodeDetails> getDatanodes() {
@@ -99,7 +96,7 @@ public void addPipeline(PipelineID pipelineId) {
   }
 
   public Set<PipelineID> getPipelineIds() {
-    return pipelineIds;
+    return Collections.unmodifiableSet(pipelineIds);
   }
 
   public HddsProtos.ExcludeListProto getProtoBuf() {
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/SCMHAUtils.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/SCMHAUtils.java
index 80e09af172b..af4e7299383 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/SCMHAUtils.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/SCMHAUtils.java
@@ -65,7 +65,7 @@ public final class SCMHAUtils {
   public static final Logger LOG =
       LoggerFactory.getLogger(SCMHAUtils.class);
 
-  private static final List<Class<? extends Exception>>
+  private static final ImmutableList<Class<? extends Exception>>
       RETRIABLE_WITH_NO_FAILOVER_EXCEPTION_LIST =
       ImmutableList.<Class<? extends Exception>>builder()
           .add(LeaderNotReadyException.class)
@@ -74,7 +74,7 @@ public final class SCMHAUtils {
           .add(ResourceUnavailableException.class)
           .build();
 
-  private static final List<Class<? extends Exception>>
+  private static final ImmutableList<Class<? extends Exception>>
       NON_RETRIABLE_EXCEPTION_LIST =
       ImmutableList.<Class<? extends Exception>>builder()
           .add(SCMException.class)
@@ -316,7 +316,7 @@ public static Throwable getExceptionForClass(Exception e,
     return null;
   }
 
-  public static List<Class<? extends
+  private static List<Class<? extends
       Exception>> getRetriableWithNoFailoverExceptionList() {
     return RETRIABLE_WITH_NO_FAILOVER_EXCEPTION_LIST;
   }
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/pipeline/Pipeline.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/pipeline/Pipeline.java
index 05d83a8b8b5..6ea92f74c19 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/pipeline/Pipeline.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/pipeline/Pipeline.java
@@ -23,7 +23,6 @@
 import java.time.ZoneId;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
@@ -113,7 +112,7 @@ private Pipeline(Builder b) {
     suggestedLeaderId = b.suggestedLeaderId;
     nodeStatus = b.nodeStatus;
     nodesInOrder = b.nodesInOrder != null ? ImmutableList.copyOf(b.nodesInOrder) : ImmutableList.of();
-    replicaIndexes = b.replicaIndexes != null ? ImmutableMap.copyOf(b.replicaIndexes) : ImmutableMap.of();
+    replicaIndexes = b.replicaIndexes;
     creationTimestamp = b.creationTimestamp != null ? b.creationTimestamp : Instant.now();
     stateEnterTime = Instant.now();
   }
@@ -541,7 +540,7 @@ public static class Builder {
     private UUID leaderId = null;
     private Instant creationTimestamp = null;
     private UUID suggestedLeaderId = null;
-    private Map<DatanodeDetails, Integer> replicaIndexes;
+    private Map<DatanodeDetails, Integer> replicaIndexes = ImmutableMap.of();
 
     public Builder() { }
 
@@ -555,13 +554,14 @@ public Builder(Pipeline pipeline) {
       this.creationTimestamp = pipeline.getCreationTimestamp();
       this.suggestedLeaderId = pipeline.getSuggestedLeaderId();
       if (nodeStatus != null) {
-        replicaIndexes = new HashMap<>();
+        final ImmutableMap.Builder<DatanodeDetails, Integer> b = ImmutableMap.builder();
         for (DatanodeDetails dn : nodeStatus.keySet()) {
           int index = pipeline.getReplicaIndex(dn);
           if (index > 0) {
-            replicaIndexes.put(dn, index);
+            b.put(dn, index);
           }
         }
+        replicaIndexes = b.build();
       }
     }
 
@@ -598,7 +598,7 @@ public Builder setNodes(List<DatanodeDetails> nodes) {
 
     public Builder setNodeOrder(List<Integer> orders) {
       // for build from ProtoBuf
-      this.nodeOrder = orders;
+      this.nodeOrder = Collections.unmodifiableList(orders);
       return this;
     }
 
@@ -624,7 +624,7 @@ public Builder setSuggestedLeaderId(UUID uuid) {
 
 
     public Builder setReplicaIndexes(Map<DatanodeDetails, Integer> indexes) {
-      this.replicaIndexes = indexes;
+      this.replicaIndexes = indexes == null ? ImmutableMap.of() : ImmutableMap.copyOf(indexes);
       return this;
     }
 
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/storage/ContainerProtocolCalls.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/storage/ContainerProtocolCalls.java
index 6bb87654c0e..66c8459a01a 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/storage/ContainerProtocolCalls.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/storage/ContainerProtocolCalls.java
@@ -746,7 +746,7 @@ public static void validateContainerResponse(
         response.getMessage(), response.getResult());
   }
 
-  public static List<Validator> getValidatorList() {
+  private static List<Validator> getValidatorList() {
     return VALIDATORS;
   }
 
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/utils/BatchOperation.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/utils/BatchOperation.java
deleted file mode 100644
index c5640cb1542..00000000000
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/utils/BatchOperation.java
+++ /dev/null
@@ -1,88 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- *  with the License.  You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- */
-
-package org.apache.hadoop.hdds.utils;
-
-import com.google.common.collect.Lists;
-
-import java.util.List;
-import java.util.Objects;
-
-/**
- * An utility class to store a batch of DB write operations.
- */
-public class BatchOperation {
-
-  /**
-   * Enum for write operations.
-   */
-  public enum Operation {
-    DELETE, PUT
-  }
-
-  private List<SingleOperation> operations =
-      Lists.newArrayList();
-
-  /**
-   * Add a PUT operation into the batch.
-   */
-  public void put(byte[] key, byte[] value) {
-    operations.add(new SingleOperation(Operation.PUT, key, value));
-  }
-
-  /**
-   * Add a DELETE operation into the batch.
-   */
-  public void delete(byte[] key) {
-    operations.add(new SingleOperation(Operation.DELETE, key, null));
-
-  }
-
-  public List<SingleOperation> getOperations() {
-    return operations;
-  }
-
-  /**
-   * A SingleOperation represents a PUT or DELETE operation
-   * and the data the operation needs to manipulates.
-   */
-  static class SingleOperation {
-
-    private final Operation opt;
-    private final byte[] key;
-    private final byte[] value;
-
-    SingleOperation(Operation opt, byte[] key, byte[] value) {
-      this.opt = opt;
-      this.key = Objects.requireNonNull(key, "key cannot be null");
-      this.value = value;
-    }
-
-    public Operation getOpt() {
-      return opt;
-    }
-
-    public byte[] getKey() {
-      return key;
-    }
-
-    public byte[] getValue() {
-      return value;
-    }
-  }
-}
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/ChecksumData.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/ChecksumData.java
index aea5c510661..4f6bfa450b0 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/ChecksumData.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/ChecksumData.java
@@ -21,6 +21,7 @@
 
 import java.util.Collections;
 import java.util.List;
+
 import org.apache.commons.lang3.builder.HashCodeBuilder;
 import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos;
 import org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos
@@ -33,7 +34,7 @@
  */
 public class ChecksumData {
 
-  private ChecksumType type;
+  private final ChecksumType type;
   // Checksum will be computed for every bytesPerChecksum number of bytes and
   // stored sequentially in checksumList
   private final int bytesPerChecksum;
@@ -47,7 +48,7 @@ public ChecksumData(ChecksumType checksumType, int bytesPerChecksum,
                       List<ByteString> checksums) {
     this.type = checksumType;
     this.bytesPerChecksum = bytesPerChecksum;
-    this.checksums = checksums;
+    this.checksums = Collections.unmodifiableList(checksums);
   }
 
   /**
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/statemachine/StateMachine.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/statemachine/StateMachine.java
index 97122e68987..4c78ca777f2 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/statemachine/StateMachine.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/common/statemachine/StateMachine.java
@@ -18,10 +18,10 @@
 
 package org.apache.hadoop.ozone.common.statemachine;
 
-import com.google.common.base.Supplier;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableSet;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -33,16 +33,16 @@
  * @param <EVENT> events allowed
  */
 public class StateMachine<STATE extends Enum<?>, EVENT extends Enum<?>> {
-  private STATE initialState;
-  private Set<STATE> finalStates;
+  private final STATE initialState;
+  private final ImmutableSet<STATE> finalStates;
 
   private final LoadingCache<EVENT, Map<STATE, STATE>> transitions =
       CacheBuilder.newBuilder().build(
-          CacheLoader.from((Supplier<Map<STATE, STATE>>) () -> new HashMap()));
+          CacheLoader.from(() -> new HashMap<>()));
 
   public StateMachine(STATE initState, Set<STATE> finalStates) {
     this.initialState = initState;
-    this.finalStates = finalStates;
+    this.finalStates = finalStates == null ? ImmutableSet.of() : ImmutableSet.copyOf(finalStates);
   }
 
   public STATE getInitialState() {
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/container/common/helpers/ChunkInfo.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/container/common/helpers/ChunkInfo.java
index cbbbb70278a..75408d65a66 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/container/common/helpers/ChunkInfo.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/container/common/helpers/ChunkInfo.java
@@ -64,7 +64,6 @@ public ChunkInfo(String chunkName, long offset, long len) {
    *
    * @param key   - Key Name.
    * @param value - Value.
-   * @throws IOException
    */
   public void addMetadata(String key, String value) throws IOException {
     synchronized (this.metadata) {
@@ -80,7 +79,6 @@ public void addMetadata(String key, String value) throws IOException {
    *
    * @param info - Protobuf class
    * @return ChunkInfo
-   * @throws IOException
    */
   public static ChunkInfo getFromProtoBuf(ContainerProtos.ChunkInfo info)
       throws IOException {
@@ -182,14 +180,9 @@ public ByteString getStripeChecksum() {
   public void setStripeChecksum(ByteString stripeChecksum) {
     this.stripeChecksum = stripeChecksum;
   }
-  
-  /**
-   * Returns Metadata associated with this Chunk.
-   *
-   * @return - Map of Key,values.
-   */
-  public Map<String, String> getMetadata() {
-    return metadata;
+
+  public String getMetadata(String key) {
+    return metadata.get(key);
   }
 
   @Override
diff --git a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/util/ShutdownHookManager.java b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/util/ShutdownHookManager.java
index b3ffe59f1d7..b3142c579f6 100644
--- a/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/util/ShutdownHookManager.java
+++ b/hadoop-hdds/common/src/main/java/org/apache/hadoop/ozone/util/ShutdownHookManager.java
@@ -18,7 +18,6 @@
 
 package org.apache.hadoop.ozone.util;
 
-import com.google.common.annotations.VisibleForTesting;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import org.apache.hadoop.hdds.HddsUtils;
 import org.apache.hadoop.hdds.conf.ConfigurationSource;
@@ -122,9 +121,7 @@ public void run() {
    * This is exposed purely for testing: do not invoke it.
    * @return the number of shutdown hooks which timed out.
    */
-  @InterfaceAudience.Private
-  @VisibleForTesting
-  int executeShutdown() {
+  private int executeShutdown() {
     int timeouts = 0;
     for (HookEntry entry: getShutdownHooksInOrder()) {
       Future<?> future = EXECUTOR.submit(entry.getHook());
@@ -190,9 +187,7 @@ public static ShutdownHookManager get() {
    * {@link org.apache.hadoop.ozone.conf.OzoneServiceConfig
    * #OZONE_SHUTDOWN_TIMEOUT_MINIMUM}
    */
-  @InterfaceAudience.Private
-  @VisibleForTesting
-  static long getShutdownTimeout(ConfigurationSource conf) {
+  private static long getShutdownTimeout(ConfigurationSource conf) {
     long duration = HddsUtils.getShutDownTimeOut(conf);
     if (duration < OZONE_SHUTDOWN_TIMEOUT_MINIMUM) {
       duration = OZONE_SHUTDOWN_TIMEOUT_MINIMUM;
@@ -204,9 +199,7 @@ static long getShutdownTimeout(ConfigurationSource conf) {
    * Private structure to store ShutdownHook, its priority and timeout
    * settings.
    */
-  @InterfaceAudience.Private
-  @VisibleForTesting
-  static class HookEntry {
+  private static class HookEntry {
     private final Runnable hook;
     private final int priority;
     private final long timeout;
@@ -260,12 +253,9 @@ TimeUnit getTimeUnit() {
   private final Set<HookEntry> hooks =
       Collections.synchronizedSet(new HashSet<>());
 
-  private AtomicBoolean shutdownInProgress = new AtomicBoolean(false);
+  private final AtomicBoolean shutdownInProgress = new AtomicBoolean(false);
 
-  //private to constructor to ensure singularity
-  @VisibleForTesting
-  @InterfaceAudience.Private
-  ShutdownHookManager() {
+  private ShutdownHookManager() {
   }
 
   /**
@@ -274,21 +264,13 @@ TimeUnit getTimeUnit() {
    *
    * @return the list of shutdownHooks in order of execution.
    */
-  @InterfaceAudience.Private
-  @VisibleForTesting
-  List<HookEntry > getShutdownHooksInOrder() {
-    List<HookEntry > list;
+  private List<HookEntry > getShutdownHooksInOrder() {
+    List<HookEntry> list;
     synchronized (hooks) {
-      list = new ArrayList<HookEntry>(hooks);
+      list = new ArrayList<>(hooks);
     }
-    Collections.sort(list, new Comparator< HookEntry >() {
-
-      //reversing comparison so highest priority hooks are first
-      @Override
-      public int compare(HookEntry o1, HookEntry o2) {
-        return o2.priority - o1.priority;
-      }
-    });
+    //reversing comparison so highest priority hooks are first
+    list.sort(Comparator.comparing(HookEntry::getPriority).reversed());
     return list;
   }
 
diff --git a/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/helpers/DatanodeIdYaml.java b/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/helpers/DatanodeIdYaml.java
index f8acbc7e2d6..85de8c08cc1 100644
--- a/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/helpers/DatanodeIdYaml.java
+++ b/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/helpers/DatanodeIdYaml.java
@@ -26,6 +26,7 @@
 import java.lang.reflect.Field;
 import java.nio.charset.StandardCharsets;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.UUID;
 
@@ -238,8 +239,9 @@ private static DatanodeDetailsYaml getDatanodeDetailsYaml(
         = new DatanodeLayoutStorage(conf, datanodeDetails.getUuidString());
 
     Map<String, Integer> portDetails = new LinkedHashMap<>();
-    if (!CollectionUtils.isEmpty(datanodeDetails.getPorts())) {
-      for (DatanodeDetails.Port port : datanodeDetails.getPorts()) {
+    final List<DatanodeDetails.Port> ports = datanodeDetails.getPorts();
+    if (!CollectionUtils.isEmpty(ports)) {
+      for (DatanodeDetails.Port port : ports) {
         Field f = null;
         try {
           f = DatanodeDetails.Port.Name.class
diff --git a/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/ChunkUtils.java b/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/ChunkUtils.java
index 7266904139d..c3f6ac92120 100644
--- a/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/ChunkUtils.java
+++ b/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/ChunkUtils.java
@@ -377,8 +377,8 @@ public static boolean isOverWriteRequested(FileChannel channel, ChunkInfo
    * @param chunkInfo - Chunk info
    * @return true if the user asks for it.
    */
-  public static boolean isOverWritePermitted(ChunkInfo chunkInfo) {
-    String overWrite = chunkInfo.getMetadata().get(OzoneConsts.CHUNK_OVERWRITE);
+  private static boolean isOverWritePermitted(ChunkInfo chunkInfo) {
+    String overWrite = chunkInfo.getMetadata(OzoneConsts.CHUNK_OVERWRITE);
     return Boolean.parseBoolean(overWrite);
   }
 
diff --git a/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/NodeDecommissionManager.java b/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/NodeDecommissionManager.java
index df224d1d449..a593062bcdb 100644
--- a/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/NodeDecommissionManager.java
+++ b/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/NodeDecommissionManager.java
@@ -254,12 +254,7 @@ private DatanodeDetails findDnWithMostRecentHeartbeat(
    * @return True if port is used by the datanode. False otherwise.
    */
   private boolean validateDNPortMatch(int port, DatanodeDetails dn) {
-    for (DatanodeDetails.Port p : dn.getPorts()) {
-      if (p.getValue() == port) {
-        return true;
-      }
-    }
-    return false;
+    return dn.hasPort(port);
   }
 
   public NodeDecommissionManager(OzoneConfiguration config, NodeManager nm, ContainerManager cm,
diff --git a/hadoop-ozone/tools/src/main/java/org/apache/hadoop/ozone/genconf/GenerateOzoneRequiredConfigurations.java b/hadoop-ozone/tools/src/main/java/org/apache/hadoop/ozone/genconf/GenerateOzoneRequiredConfigurations.java
index cfdc924486a..927e9186ff5 100644
--- a/hadoop-ozone/tools/src/main/java/org/apache/hadoop/ozone/genconf/GenerateOzoneRequiredConfigurations.java
+++ b/hadoop-ozone/tools/src/main/java/org/apache/hadoop/ozone/genconf/GenerateOzoneRequiredConfigurations.java
@@ -159,8 +159,7 @@ public static void generateConfigurations(String path,
     }
 
     OzoneConfiguration.XMLConfiguration generatedConfig =
-        new OzoneConfiguration.XMLConfiguration();
-    generatedConfig.setProperties(requiredProperties);
+        new OzoneConfiguration.XMLConfiguration(requiredProperties);
 
     File output = new File(path, "ozone-site.xml");
     if (output.createNewFile()) {