Checkstyle rule for redundant initialization

cdap-api/src/main/java/io/cdap/cdap/api/data/batch/SplitReaderAdapter.java

@@ -34,8 +34,8 @@ public SplitReaderAdapter(SplitReader<FROM_KEY, FROM_VALUE> delegate) {
   protected abstract TO_KEY convertKey(FROM_KEY key);
   protected abstract TO_VALUE convertValue(FROM_VALUE value);
 
-  private TO_KEY nextKey = null;
-  private TO_VALUE nextValue = null;
+  private TO_KEY nextKey;
+  private TO_VALUE nextValue;
 
   @Override
   public void initialize(Split split) throws InterruptedException {

cdap-api/src/main/java/io/cdap/cdap/api/dataset/lib/CounterTimeseriesTable.java

@@ -147,7 +147,7 @@ public Iterator<Counter> read(byte[] counter, long startTime, long endTime,
     // Returns a limiting Iterator
     return new Iterator<Counter>() {
 
-      private int count = 0;
+      private int count;
 
       @Override
       public boolean hasNext() {

cdap-api/src/main/java/io/cdap/cdap/api/dataset/lib/FileSetProperties.java

@@ -282,7 +282,7 @@ public static Map<String, String> propertiesWithPrefix(Map<String, String> prope
    */
   public static class Builder extends ExploreProperties.AbstractBuilder<Builder> {
 
-    private String format = null;
+    private String format;
 
     /**
      * Package visible default constructor, to allow sub-classing by other datasets in this package.

cdap-api/src/main/java/io/cdap/cdap/api/dataset/lib/KeyValueTable.java

@@ -248,7 +248,7 @@ public CloseableIterator<KeyValue<byte[], byte[]>> scan(byte[] startRow, byte[]
     final Scanner scanner = table.scan(startRow, stopRow);
 
     return new AbstractCloseableIterator<KeyValue<byte[], byte[]>>() {
-      private boolean closed = false;
+      private boolean closed;
       @Override
       protected KeyValue<byte[], byte[]> computeNext() {
         if (closed) {

cdap-api/src/main/java/io/cdap/cdap/api/dataset/lib/TimeseriesTable.java

@@ -159,7 +159,7 @@ public final Iterator<Entry> read(byte[] key, long startTime, long endTime,
     }
 
     return new Iterator<Entry>() {
-      int count = 0;
+      int count;
 
       @Override
       public boolean hasNext() {

cdap-api/src/main/java/io/cdap/cdap/api/dataset/lib/partitioned/PartitionAcceptor.java

@@ -50,7 +50,7 @@ enum Return {
    */
   final class Limit implements PartitionAcceptor {
 
-    private int count = 0;
+    private int count;
     private int limit;
 
     public Limit(int limit) {

cdap-api/src/main/java/io/cdap/cdap/api/macro/MacroParserOptions.java

@@ -82,9 +82,9 @@ public static class Builder {
     private boolean evaluateLookups = true;
     private boolean evaluateFunctions = true;
     private boolean escapingEnabled = true;
-    private boolean skipInvalid = false;
+    private boolean skipInvalid;
     private int maxRecurseDepth = 10;
-    private Set<String> functionWhitelist = new HashSet<>();
+    private final Set<String> functionWhitelist = new HashSet<>();
 
     public Builder disableLookups() {
       evaluateLookups = false;

cdap-api/src/main/java/io/cdap/cdap/internal/io/TypeRepresentation.java

@@ -38,7 +38,7 @@ public final class TypeRepresentation implements ParameterizedType {
   private final String rawType;
   private final TypeRepresentation enclosingType;
   private final TypeRepresentation[] parameters;
-  private transient ClassLoader classLoader = null;
+  private transient ClassLoader classLoader;
 
   /**
    * Set the class loader to be used by toType(), getRawType(), etc.

cdap-app-fabric/src/main/java/io/cdap/cdap/hive/ExploreUtils.java

@@ -66,7 +66,7 @@ public URL apply(File file) {
     }
   };
 
-  private static ClassLoader exploreClassLoader = null;
+  private static ClassLoader exploreClassLoader;
 
   /**
    * Builds a class loader with the class path provided.

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/preview/PreviewDataSubscriberService.java

@@ -67,8 +67,8 @@ public class PreviewDataSubscriberService extends AbstractMessagingSubscriberSer
   private final MultiThreadMessagingContext messagingContext;
   private final TransactionRunner transactionRunner;
   private final int maxRetriesOnError;
-  private int errorCount = 0;
-  private String erroredMessageId = null;
+  private int errorCount;
+  private String erroredMessageId;
   private MetricsCollectionService metricsCollectionService;
 
   /**

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/preview/PreviewTMSLogSubscriber.java

@@ -55,8 +55,8 @@ public class PreviewTMSLogSubscriber extends AbstractMessagingSubscriberService<
   private final TransactionRunner transactionRunner;
   private final RemoteExecutionLogProcessor logProcessor;
   private final int maxRetriesOnError;
-  private int errorCount = 0;
-  private String erroredMessageId = null;
+  private int errorCount;
+  private String erroredMessageId;
 
   @Inject
   PreviewTMSLogSubscriber(CConfiguration cConf,

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/runtime/batch/MapperWrapper.java

@@ -174,8 +174,8 @@ private WrappedMapper.Context createAutoFlushingContext(final Context context,
 
     @SuppressWarnings("unchecked")
     WrappedMapper.Context flushingContext = new WrappedMapper().new Context(context) {
-      private int processedRecords = 0;
-      private long nextTimeToReportMetrics = 0L;
+      private int processedRecords;
+      private long nextTimeToReportMetrics;
 
       @Override
       public boolean nextKeyValue() throws IOException, InterruptedException {

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/runtime/batch/ReducerWrapper.java

@@ -145,8 +145,8 @@ private WrappedReducer.Context createAutoFlushingContext(final Context context,
 
     @SuppressWarnings("unchecked")
     WrappedReducer.Context flushingContext = new WrappedReducer().new Context(context) {
-      private int processedRecords = 0;
-      private long nextTimeToReportMetrics = 0L;
+      private int processedRecords;
+      private long nextTimeToReportMetrics;
 
       @Override
       public boolean nextKeyValue() throws IOException, InterruptedException {

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/runtime/schedule/queue/SimpleJob.java

@@ -33,7 +33,7 @@ public final class SimpleJob implements Job {
   private final List<Notification> notifications;
   private final State state;
   private final long scheduleLastUpdatedTime;
-  private Long deleteTimeMillis = null;
+  private Long deleteTimeMillis;
 
   /**
    * @param scheduleLastUpdatedTime the last modification time of the schedule, at the time this job is created.

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/worker/TaskWorkerHttpHandlerInternal.java

@@ -244,7 +244,7 @@ private static class RunnableTaskBodyProducer extends BodyProducer {
     private final BiConsumer<Boolean, TaskDetails> stopper;
     private final TaskDetails taskDetails;
     private final boolean terminateOnComplete;
-    private boolean done = false;
+    private boolean done;
 
     RunnableTaskBodyProducer(RunnableTaskContext context, BiConsumer<Boolean, TaskDetails> stopper,
                              TaskDetails taskDetails) {

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/worker/system/SystemWorkerHttpHandlerInternal.java

@@ -140,7 +140,7 @@ private String exceptionToJson(Exception ex) {
   private static class RunnableTaskBodyProducer extends BodyProducer {
     private final ByteBuffer response;
     private final TaskDetails taskDetails;
-    private boolean done = false;
+    private boolean done;
 
     RunnableTaskBodyProducer(RunnableTaskContext context, TaskDetails taskDetails) {
       this.response = context.getResult();

cdap-app-fabric/src/main/java/io/cdap/cdap/internal/app/workflow/DefaultWorkflowConfigurer.java

@@ -68,7 +68,7 @@ public class DefaultWorkflowConfigurer extends AbstractConfigurer
   private final AppDeploymentRuntimeInfo runtimeInfo;
   private final List<WorkflowNode> nodes = Lists.newArrayList();
 
-  private int nodeIdentifier = 0;
+  private int nodeIdentifier;
   private String name;
   private String description;
   private Map<String, String> properties;

cdap-app-fabric/src/main/java/io/cdap/cdap/metadata/MetadataSubscriberService.java

@@ -115,11 +115,11 @@ public class MetadataSubscriberService extends AbstractMessagingSubscriberServic
   private final int maxRetriesOnConflict;
   private final MetricsCollectionService metricsCollectionService;
 
-  private String conflictMessageId = null;
-  private int conflictCount = 0;
+  private String conflictMessageId;
+  private int conflictCount;
 
-  private boolean didBackfill = false;
-  private int backfillAttempts = 0;
+  private boolean didBackfill;
+  private int backfillAttempts;
 
   @Inject
   MetadataSubscriberService(CConfiguration cConf, MessagingService messagingService,

cdap-app-fabric/src/main/java/io/cdap/cdap/scheduler/ConstraintCheckerService.java

@@ -67,7 +67,7 @@ class ConstraintCheckerService extends AbstractIdleService {
   private final TransactionRunner transactionRunner;
   private ScheduleTaskRunner taskRunner;
   private ListeningExecutorService taskExecutorService;
-  private volatile boolean stopping = false;
+  private volatile boolean stopping;
 
   @Inject
   ConstraintCheckerService(Store store,

cdap-app-fabric/src/main/java/io/cdap/cdap/security/ApplicationSecurity.java

@@ -109,7 +109,7 @@ public static Builder builder() {
    */
   public static class Builder {
     private final PermissionCollection perms;
-    private Class<?> klass = null;
+    private Class<?> klass;
 
     /**
      * Invoked by the {@link #builder()}.

cdap-app-fabric/src/test/java/io/cdap/cdap/AppWithMisbehavedDataset.java

@@ -59,7 +59,7 @@ public void configure() {
    */
   public static class MisbehavedDataset extends AbstractDataset {
 
-    private boolean active = false;
+    private boolean active;
 
     public MisbehavedDataset(DatasetSpecification spec, @EmbeddedDataset("t") Table table) {
       super(spec.getName(), table);

cdap-app-fabric/src/test/java/io/cdap/cdap/internal/app/program/ProgramStateWriterWithHeartBeatTest.java

@@ -45,7 +45,7 @@
 
 public class ProgramStateWriterWithHeartBeatTest {
   private static class MockProgramStatePublisher implements ProgramStatePublisher {
-    long heartBeatCount = 0;
+    long heartBeatCount;
 
     @Override
     public void publish(Notification.Type notificationType, Map<String, String> properties) {

cdap-app-fabric/src/test/java/io/cdap/cdap/internal/app/runtime/batch/AppWithMapReduceUsingRuntimeDatasets.java

@@ -116,7 +116,7 @@ public static class FileMapper
     extends Mapper<LongWritable, Text, Text, LongWritable>
     implements ProgramLifecycle<MapReduceTaskContext> {
 
-    private KeyValueTable counters = null;
+    private KeyValueTable counters;
 
     public static final String ONLY_KEY = "x";
     @Override
@@ -141,7 +141,7 @@ public static class FileReducer
     extends Reducer<Text, LongWritable, String, Long>
     implements ProgramLifecycle<MapReduceTaskContext> {
 
-    private KeyValueTable counters = null;
+    private KeyValueTable counters;
 
     public void reduce(Text key, Iterable<LongWritable> values, Context context)
                               throws IOException, InterruptedException  {

cdap-app-fabric/src/test/java/io/cdap/cdap/internal/app/runtime/batch/AppWithTxAware.java

@@ -76,8 +76,8 @@ protected void map(Integer key, Integer value, Context context) throws IOExcepti
   }
 
   public static class PedanticTxAware extends AbstractDataset implements BatchReadable<Integer, Integer> {
-    private Transaction tx = null;
-    private Transaction remembered = null;
+    private Transaction tx;
+    private Transaction remembered;
 
     public PedanticTxAware(DatasetSpecification spec, @EmbeddedDataset("t") Table embedded) {
       super(spec.getName(), embedded);

cdap-app-fabric/src/test/java/io/cdap/cdap/internal/app/runtime/monitor/proxy/TestHandler.java

@@ -57,7 +57,7 @@ public void chunk(FullHttpRequest request, HttpResponder responder) {
 
     responder.sendContent(HttpResponseStatus.OK, new BodyProducer() {
 
-      int count = 0;
+      int count;
 
       @Override
       public ByteBuf nextChunk() {

cdap-app-fabric/src/test/java/io/cdap/cdap/internal/app/services/http/handlers/ProgramLifecycleHttpHandlerInternalTest.java

@@ -44,7 +44,7 @@ public class ProgramLifecycleHttpHandlerInternalTest extends AppFabricTestBase {
   private static final String STOPPED = "STOPPED";
   private static final String RUNNING = "RUNNING";
 
-  private static ProgramRunRecordFetcher programRunRecordFetcher = null;
+  private static ProgramRunRecordFetcher programRunRecordFetcher;
 
   @BeforeClass
   public static void init() {

cdap-app-fabric/src/test/java/io/cdap/cdap/internal/provision/MockProvisioner.java

@@ -181,10 +181,10 @@ private void validateContext(ProvisionerContext context) {
    */
   public static class PropertyBuilder {
     private Integer failRetryablyEveryN;
-    private boolean failCreate = false;
-    private boolean failGet = false;
-    private boolean failInit = false;
-    private boolean failDelete = false;
+    private boolean failCreate;
+    private boolean failGet;
+    private boolean failInit;
+    private boolean failDelete;
     private long waitCreateMillis = -1L;
     private long waitDeleteMillis = -1L;
     private ClusterStatus firstClusterStatus;

cdap-app-fabric/src/test/java/io/cdap/cdap/internal/tethering/MockTetheringServerHandler.java

@@ -39,7 +39,7 @@
 public class MockTetheringServerHandler extends AbstractHttpHandler {
   private static final Gson GSON = new Gson();
   private HttpResponseStatus responseStatus = HttpResponseStatus.OK;
-  private boolean tetheringCreated = false;
+  private boolean tetheringCreated;
 
   @GET
   @Path("/tethering/controlchannels/{peer}")

cdap-app-fabric/src/test/java/io/cdap/cdap/metadata/PreferencesFetcherInternalTest.java

@@ -47,7 +47,7 @@ public enum PreferencesFetcherType {
     REMOTE,
   };
 
-  private PreferencesFetcherType fetcherType = null;
+  private PreferencesFetcherType fetcherType;
 
   public PreferencesFetcherInternalTest(PreferencesFetcherType type) {
     this.fetcherType = type;

cdap-app-fabric/src/test/java/org/apache/hadoop/util/Shell.java

@@ -255,7 +255,7 @@ public static String[] getRunScriptCommand(File script) {
   public static final String READ_LINK_COMMAND = "readlink";
 
   /**Time after which the executing script would be timedout*/
-  protected long timeOutInterval = 0L;
+  protected long timeOutInterval;
   /** If or not script timed out*/
   private AtomicBoolean timedOut;
 

cdap-app-templates/cdap-etl/cdap-data-pipeline-base/src/main/java/io/cdap/cdap/datapipeline/SmartWorkflow.java

@@ -150,8 +150,8 @@ public class SmartWorkflow extends AbstractWorkflow {
   private Metrics workflowMetrics;
   private ETLBatchConfig config;
   private BatchPipelineSpec spec;
-  private int connectorNum = 0;
-  private int publisherNum = 0;
+  private int connectorNum;
+  private int publisherNum;
 
   public SmartWorkflow(ETLBatchConfig config, Set<String> supportedPluginTypes,
                        ApplicationConfigurer applicationConfigurer) {

cdap-app-templates/cdap-etl/cdap-data-pipeline-base/src/test/java/io/cdap/cdap/datapipeline/AutoJoinerTest.java

@@ -75,7 +75,7 @@ public class AutoJoinerTest extends HydratorTestBase {
   private static final ArtifactId APP_ARTIFACT_ID = NamespaceId.DEFAULT.artifact("app", "1.0.0");
   private static final ArtifactSummary APP_ARTIFACT = new ArtifactSummary("app", "1.0.0");
 
-  private static int startCount = 0;
+  private static int startCount;
   private static final Schema USER_SCHEMA = Schema.recordOf(
     "user",
     Schema.Field.of("region", Schema.of(Schema.Type.STRING)),

cdap-app-templates/cdap-etl/cdap-data-pipeline-base/src/test/java/io/cdap/cdap/datapipeline/DataPipelineConnectionTest.java

@@ -133,7 +133,7 @@ public class DataPipelineConnectionTest extends HydratorTestBase {
     new GsonBuilder().registerTypeAdapter(Schema.class, new SchemaTypeAdapter())
       .registerTypeAdapter(SampleResponse.class, new SampleResponseCodec()).setPrettyPrinting().create();
 
-  private static int startCount = 0;
+  private static int startCount;
 
   @ClassRule
   public static final TestConfiguration CONFIG =

cdap-app-templates/cdap-etl/cdap-data-pipeline-base/src/test/java/io/cdap/cdap/datapipeline/DataPipelineTest.java

@@ -176,7 +176,7 @@ public class DataPipelineTest extends HydratorTestBase {
   private static final ArtifactId OLD_APP_ARTIFACT_ID = NamespaceId.DEFAULT.artifact("app", "0.0.9");
 
   private static final ArtifactSummary APP_ARTIFACT_RANGE = new ArtifactSummary("app", "[0.1.0,1.1.0)");
-  private static int startCount = 0;
+  private static int startCount;
 
   @ClassRule
   public static final TestConfiguration CONFIG = new TestConfiguration(Constants.Explore.EXPLORE_ENABLED, false,

cdap-app-templates/cdap-etl/cdap-data-pipeline-base/src/test/java/io/cdap/cdap/datapipeline/ReducibleAggregatorTestBase.java

@@ -63,7 +63,7 @@ public class ReducibleAggregatorTestBase extends HydratorTestBase {
   private static final ArtifactId APP_ARTIFACT_ID = NamespaceId.DEFAULT.artifact("app", "1.0.0");
   private static final ArtifactSummary APP_ARTIFACT = new ArtifactSummary("app", "1.0.0");
 
-  private static int startCount = 0;
+  private static int startCount;
 
   @ClassRule
   public static final TestConfiguration CONFIG = new TestConfiguration(

cdap-app-templates/cdap-etl/cdap-data-pipeline-base/src/test/java/io/cdap/cdap/datapipeline/preview/PreviewDataPipelineTest.java

@@ -85,7 +85,7 @@ public class PreviewDataPipelineTest extends HydratorTestBase {
   private static final ArtifactId APP_ARTIFACT_ID = NamespaceId.DEFAULT.artifact("app", "1.0.0");
   private static final ArtifactSummary APP_ARTIFACT = new ArtifactSummary("app", "1.0.0");
   private static final ArtifactSummary APP_ARTIFACT_RANGE = new ArtifactSummary("app", "[0.1.0,1.1.0)");
-  private static int startCount = 0;
+  private static int startCount;
   @ClassRule
   public static final TestConfiguration CONFIG = new TestConfiguration(Constants.Explore.EXPLORE_ENABLED, false,
                                                                        Constants.Security.Store.PROVIDER, "file",

cdap-app-templates/cdap-etl/cdap-data-streams-base/src/test/java/io/cdap/cdap/datastreams/DataStreamsSparkSinkTest.java

@@ -57,7 +57,7 @@ public class DataStreamsSparkSinkTest  extends HydratorTestBase {
 
   private static final ArtifactId APP_ARTIFACT_ID = NamespaceId.DEFAULT.artifact("app", "1.0.0");
   private static final ArtifactSummary APP_ARTIFACT = new ArtifactSummary("app", "1.0.0");
-  private static int startCount = 0;
+  private static int startCount;
   @ClassRule
   public static final TestConfiguration CONFIG = new TestConfiguration(Constants.Explore.EXPLORE_ENABLED, false,
                                                                        Constants.AppFabric.SPARK_COMPAT,

cdap-app-templates/cdap-etl/cdap-data-streams-base/src/test/java/io/cdap/cdap/datastreams/DataStreamsTest.java

@@ -104,7 +104,7 @@ public class DataStreamsTest extends HydratorTestBase {
   private static final ArtifactId APP_ARTIFACT_ID = NamespaceId.DEFAULT.artifact("app", "1.0.0");
   private static final ArtifactSummary APP_ARTIFACT = new ArtifactSummary("app", "1.0.0");
   private static String checkpointDir;
-  private static int startCount = 0;
+  private static int startCount;
   @ClassRule
   public static final TestConfiguration CONFIG = new TestConfiguration(Constants.Explore.EXPLORE_ENABLED, false,
                                                                        Constants.AppFabric.SPARK_COMPAT,

cdap-app-templates/cdap-etl/cdap-data-streams-base/src/test/java/io/cdap/cdap/datastreams/preview/PreviewDataStreamsTest.java

@@ -70,7 +70,7 @@ public class PreviewDataStreamsTest extends HydratorTestBase {
 
   private static final ArtifactId APP_ARTIFACT_ID = NamespaceId.DEFAULT.artifact("app", "1.0.0");
   private static final ArtifactSummary APP_ARTIFACT = new ArtifactSummary("app", "1.0.0");
-  private static int startCount = 0;
+  private static int startCount;
   @ClassRule
   public static final TestConfiguration CONFIG = new TestConfiguration(Constants.Explore.EXPLORE_ENABLED, false,
                                                                        Constants.AppFabric.SPARK_COMPAT,

cdap-app-templates/cdap-etl/cdap-etl-core/src/main/java/io/cdap/cdap/etl/common/record/StructuredRecordComparator.java

@@ -271,7 +271,7 @@ public Iterator<Object> iterator() {
         return ((Collection<Object>) array).iterator();
       }
       return new Iterator<Object>() {
-        private int curr = 0;
+        private int curr;
 
         @Override
         public boolean hasNext() {