diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseManager.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseManager.java
index e3de134..fc73374 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseManager.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseManager.java
@@ -228,76 +228,89 @@
 
     @Override
     public boolean putIfAbsent(String tableName, String key, byte[] value) {
-        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder().putIfAbsent(tableName, key, value).build();
+        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder()
+                    .putIfAbsent(tableName, key, value).build();
         WriteResult writeResult = batchWrite(batchRequest).getAsList().get(0);
         if (writeResult.status().equals(WriteStatus.OK)) {
             return true;
         } else if (writeResult.status().equals(WriteStatus.PRECONDITION_VIOLATION)) {
             return false;
         }
-        throw new DatabaseException("putIfAbsent failed due to status: " + writeResult.status());
+        throw new DatabaseException("putIfAbsent failed due to status: "
+                    + writeResult.status());
     }
 
     @Override
     public boolean putIfVersionMatches(String tableName, String key,
             byte[] value, long version) {
-        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder().putIfVersionMatches(tableName, key, value, version).build();
+        BatchWriteRequest batchRequest =
+                new BatchWriteRequest.Builder()
+                    .putIfVersionMatches(tableName, key, value, version).build();
         WriteResult writeResult = batchWrite(batchRequest).getAsList().get(0);
         if (writeResult.status().equals(WriteStatus.OK)) {
             return true;
         } else if (writeResult.status().equals(WriteStatus.PRECONDITION_VIOLATION)) {
             return false;
         }
-        throw new DatabaseException("putIfVersionMatches failed due to status: " + writeResult.status());
+        throw new DatabaseException("putIfVersionMatches failed due to status: "
+                    + writeResult.status());
     }
 
     @Override
     public boolean putIfValueMatches(String tableName, String key,
             byte[] oldValue, byte[] newValue) {
-        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder().putIfValueMatches(tableName, key, oldValue, newValue).build();
+        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder()
+                    .putIfValueMatches(tableName, key, oldValue, newValue).build();
         WriteResult writeResult = batchWrite(batchRequest).getAsList().get(0);
         if (writeResult.status().equals(WriteStatus.OK)) {
             return true;
         } else if (writeResult.status().equals(WriteStatus.PRECONDITION_VIOLATION)) {
             return false;
         }
-        throw new DatabaseException("putIfValueMatches failed due to status: " + writeResult.status());
+        throw new DatabaseException("putIfValueMatches failed due to status: "
+                    + writeResult.status());
     }
 
     @Override
     public VersionedValue remove(String tableName, String key) {
-        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder().remove(tableName, key).build();
+        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder()
+                    .remove(tableName, key).build();
         WriteResult writeResult = batchWrite(batchRequest).getAsList().get(0);
         if (writeResult.status().equals(WriteStatus.OK)) {
             return writeResult.previousValue();
         }
-        throw new DatabaseException("remove failed due to status: " + writeResult.status());
+        throw new DatabaseException("remove failed due to status: "
+                    + writeResult.status());
     }
 
     @Override
     public boolean removeIfVersionMatches(String tableName, String key,
             long version) {
-        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder().removeIfVersionMatches(tableName, key, version).build();
+        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder()
+                    .removeIfVersionMatches(tableName, key, version).build();
         WriteResult writeResult = batchWrite(batchRequest).getAsList().get(0);
         if (writeResult.status().equals(WriteStatus.OK)) {
             return true;
         } else if (writeResult.status().equals(WriteStatus.PRECONDITION_VIOLATION)) {
             return false;
         }
-        throw new DatabaseException("removeIfVersionMatches failed due to status: " + writeResult.status());
+        throw new DatabaseException("removeIfVersionMatches failed due to status: "
+                    + writeResult.status());
     }
 
     @Override
     public boolean removeIfValueMatches(String tableName, String key,
             byte[] value) {
-        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder().removeIfValueMatches(tableName, key, value).build();
+        BatchWriteRequest batchRequest = new BatchWriteRequest.Builder()
+                    .removeIfValueMatches(tableName, key, value).build();
         WriteResult writeResult = batchWrite(batchRequest).getAsList().get(0);
         if (writeResult.status().equals(WriteStatus.OK)) {
             return true;
         } else if (writeResult.status().equals(WriteStatus.PRECONDITION_VIOLATION)) {
             return false;
         }
-        throw new DatabaseException("removeIfValueMatches failed due to status: " + writeResult.status());
+        throw new DatabaseException("removeIfValueMatches failed due to status: "
+                    + writeResult.status());
     }
 
     @Override
@@ -404,4 +417,4 @@
         }
         return null;
     }
-}
+}
\ No newline at end of file
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java
index 17b174c..7fc0ac0 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java
@@ -47,7 +47,7 @@
     private final Logger log = getLogger(getClass());
 
     // message subject for database update notifications.
-    public static MessageSubject DATABASE_UPDATE_EVENTS =
+    public static final MessageSubject DATABASE_UPDATE_EVENTS =
             new MessageSubject("database-update-events");
 
     // serializer used for snapshot
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventHandler.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventHandler.java
index 58d5446..5eca21f 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventHandler.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventHandler.java
@@ -38,11 +38,16 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class DatabaseUpdateEventHandler implements DatabaseUpdateEventListener, EventHandler<LeaderElectEvent> {
+/**
+ * Database update event handler.
+ */
+public class DatabaseUpdateEventHandler implements
+    DatabaseUpdateEventListener, EventHandler<LeaderElectEvent> {
 
     private final Logger log = LoggerFactory.getLogger(getClass());
 
-    public final static MessageSubject DATABASE_UPDATES = new MessageSubject("database-update-event");
+    public static final MessageSubject DATABASE_UPDATES =
+            new MessageSubject("database-update-event");
 
     private DatabaseService databaseService;
     private ClusterService cluster;
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventListener.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventListener.java
index f7b147f..d97191c 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventListener.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseUpdateEventListener.java
@@ -16,23 +16,26 @@
 
 package org.onlab.onos.store.service.impl;
 
+/**
+ * Interface of database update event listeners.
+ */
 public interface DatabaseUpdateEventListener {
-    
+
     /**
-     * 
-     * @param event
+     * Notifies listeners of a table modified event.
+     * @param event table modification event.
      */
     public void tableModified(TableModificationEvent event);
-    
+
     /**
-     * 
+     * Notifies listeners of a table created event.
      * @param tableName
      * @param expirationTimeMillis
      */
     public void tableCreated(String tableName, int expirationTimeMillis);
-    
+
     /**
-     * 
+     * Notifies listeners of a table deleted event.
      * @param tableName
      */
     public void tableDeleted(String tableName);
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLock.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLock.java
index eaae063..4a7367d 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLock.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLock.java
@@ -69,7 +69,7 @@
     public boolean tryLock(
             long waitTimeMillis,
             int leaseDurationMillis) {
-        if (tryLock(leaseDurationMillis) == false) {
+        if (!tryLock(leaseDurationMillis)) {
             CompletableFuture<Void> future =
                     lockManager.lockIfAvailable(this, waitTimeMillis, leaseDurationMillis);
             try {
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLockManager.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLockManager.java
index c87ab37..f83b042 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLockManager.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DistributedLockManager.java
@@ -80,7 +80,10 @@
         throw new UnsupportedOperationException();
     }
 
-    protected CompletableFuture<Void> lockIfAvailable(Lock lock, long waitTimeMillis, int leaseDurationMillis) {
+    protected CompletableFuture<Void> lockIfAvailable(
+            Lock lock,
+            long waitTimeMillis,
+            int leaseDurationMillis) {
         CompletableFuture<Void> future = new CompletableFuture<>();
         locksToAcquire.put(
                 lock.path(),
@@ -103,7 +106,9 @@
 
             if (event.type() == TableModificationEvent.Type.ROW_DELETED) {
                 List<LockRequest> existingRequests = locksToAcquire.get(path);
-                if (existingRequests == null) return;
+                if (existingRequests == null) {
+                    return;
+                }
 
                 Iterator<LockRequest> existingRequestIterator = existingRequests.iterator();
                 while (existingRequestIterator.hasNext()) {
@@ -111,7 +116,7 @@
                     if (request.expirationTime().isAfter(DateTime.now())) {
                         existingRequestIterator.remove();
                     } else {
-                        if (request.lock().tryLock(request.leaseDurationMillis()) == true) {
+                        if (request.lock().tryLock(request.leaseDurationMillis())) {
                             request.future().complete(null);
                             existingRequests.remove(0);
                         }
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/TableModificationEvent.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/TableModificationEvent.java
index 25956de..885c9fa 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/TableModificationEvent.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/TableModificationEvent.java
@@ -1,25 +1,50 @@
 package org.onlab.onos.store.service.impl;
 
-public class TableModificationEvent {
+/**
+ * A table modification event.
+ */
+public final class TableModificationEvent {
 
+    /**
+     * Type of table modification event.
+     *
+     */
     public enum Type {
         ROW_ADDED,
         ROW_DELETED,
         ROW_UPDATED
     }
-    
+
     private final String tableName;
     private final String key;
     private final Type type;
 
+    /**
+     * Creates a new row deleted table modification event.
+     * @param tableName table name.
+     * @param key row key
+     * @return table modification event.
+     */
     public static TableModificationEvent rowDeleted(String tableName, String key) {
         return new TableModificationEvent(tableName, key, Type.ROW_DELETED);
     }
-    
+
+    /**
+     * Creates a new row added table modification event.
+     * @param tableName table name.
+     * @param key row key
+     * @return table modification event.
+     */
     public static TableModificationEvent rowAdded(String tableName, String key) {
         return new TableModificationEvent(tableName, key, Type.ROW_ADDED);
     }
-    
+
+    /**
+     * Creates a new row updated table modification event.
+     * @param tableName table name.
+     * @param key row key
+     * @return table modification event.
+     */
     public static TableModificationEvent rowUpdated(String tableName, String key) {
         return new TableModificationEvent(tableName, key, Type.ROW_UPDATED);
     }
@@ -30,14 +55,26 @@
         this.type = type;
     }
 
+    /**
+     * Returns name of table this event is for.
+     * @return table name
+     */
     public String tableName() {
         return tableName;
     }
 
+    /**
+     * Returns the row key this event is for.
+     * @return row key
+     */
     public String key() {
         return key;
     }
 
+    /**
+     * Returns the type of table modification event.
+     * @return event type.
+     */
     public Type type() {
         return type;
     }