Upgrade checkstyle to version 7.5

This commit upgrades the checkstyle configuration from version 5.9 to
version 7.5, the latest version as of today. The main enhancement
obtained via this upgrade is better detection of redundant modifiers.

Relates #22960

buildSrc/src/main/groovy/org/elasticsearch/gradle/precommit/PrecommitTasks.groovy

@@ -139,6 +139,7 @@ class PrecommitTasks {
             configProperties = [
                 suppressions: checkstyleSuppressions
             ]
+            toolVersion = 7.5
         }
         for (String taskName : ['checkstyleMain', 'checkstyleTest']) {
             Task task = project.tasks.findByName(taskName)

client/benchmark/src/main/java/org/elasticsearch/client/benchmark/ops/bulk/BulkBenchmarkTask.java

@@ -95,7 +95,7 @@ private static final class LoadGenerator {
         private final BlockingQueue<List<String>> bulkQueue;
         private final int bulkSize;
 
-        public LoadGenerator(Path bulkDataFile, BlockingQueue<List<String>> bulkQueue, int bulkSize) {
+        LoadGenerator(Path bulkDataFile, BlockingQueue<List<String>> bulkQueue, int bulkSize) {
             this.bulkDataFile = bulkDataFile;
             this.bulkQueue = bulkQueue;
             this.bulkSize = bulkSize;
@@ -143,7 +143,7 @@ private static final class BulkIndexer implements Runnable {
         private final BulkRequestExecutor bulkRequestExecutor;
         private final SampleRecorder sampleRecorder;
 
-        public BulkIndexer(BlockingQueue<List<String>> bulkData, int warmupIterations, int measurementIterations,
+        BulkIndexer(BlockingQueue<List<String>> bulkData, int warmupIterations, int measurementIterations,
                            SampleRecorder sampleRecorder, BulkRequestExecutor bulkRequestExecutor) {
             this.bulkData = bulkData;
             this.warmupIterations = warmupIterations;

client/benchmark/src/main/java/org/elasticsearch/client/benchmark/rest/RestClientBenchmark.java

@@ -73,7 +73,7 @@ private static final class RestBulkRequestExecutor implements BulkRequestExecuto
         private final RestClient client;
         private final String actionMetaData;
 
-        public RestBulkRequestExecutor(RestClient client, String index, String type) {
+        RestBulkRequestExecutor(RestClient client, String index, String type) {
             this.client = client;
             this.actionMetaData = String.format(Locale.ROOT, "{ \"index\" : { \"_index\" : \"%s\", \"_type\" : \"%s\" } }%n", index, type);
         }

client/benchmark/src/main/java/org/elasticsearch/client/benchmark/transport/TransportClientBenchmark.java

@@ -70,7 +70,7 @@ private static final class TransportBulkRequestExecutor implements BulkRequestEx
         private final String indexName;
         private final String typeName;
 
-        public TransportBulkRequestExecutor(TransportClient client, String indexName, String typeName) {
+        TransportBulkRequestExecutor(TransportClient client, String indexName, String typeName) {
             this.client = client;
             this.indexName = indexName;
             this.typeName = typeName;

client/client-benchmark-noop-api-plugin/src/main/java/org/elasticsearch/plugin/noop/action/bulk/RestNoopBulkAction.java

@@ -89,7 +89,7 @@ private static class BulkRestBuilderListener extends RestBuilderListener<BulkReq
         private final RestRequest request;
 
 
-        public BulkRestBuilderListener(RestChannel channel, RestRequest request) {
+        BulkRestBuilderListener(RestChannel channel, RestRequest request) {
             super(channel);
             this.request = request;
         }

client/rest/src/main/java/org/elasticsearch/client/HttpAsyncResponseConsumerFactory.java

@@ -53,7 +53,7 @@ class HeapBufferedResponseConsumerFactory implements HttpAsyncResponseConsumerFa
 
         private final int bufferLimit;
 
-        public HeapBufferedResponseConsumerFactory(int bufferLimitBytes) {
+        HeapBufferedResponseConsumerFactory(int bufferLimitBytes) {
             this.bufferLimit = bufferLimitBytes;
         }
 

client/rest/src/main/java/org/elasticsearch/client/RestClient.java

@@ -705,7 +705,7 @@ private static class HostTuple<T> {
         public final T hosts;
         public final AuthCache authCache;
 
-        public HostTuple(final T hosts, final AuthCache authCache) {
+        HostTuple(final T hosts, final AuthCache authCache) {
             this.hosts = hosts;
             this.authCache = authCache;
         }

client/rest/src/test/java/org/elasticsearch/client/RestClientSingleHostIntegTests.java

@@ -237,7 +237,7 @@ public void testGetWithBody() throws IOException {
     public void testPreemptiveAuthEnabled() throws IOException  {
         final String[] methods = { "POST", "PUT", "GET", "DELETE" };
 
-        try (final RestClient restClient = createRestClient(true, true)) {
+        try (RestClient restClient = createRestClient(true, true)) {
             for (final String method : methods) {
                 final Response response = bodyTest(restClient, method);
 
@@ -252,7 +252,7 @@ public void testPreemptiveAuthEnabled() throws IOException  {
     public void testPreemptiveAuthDisabled() throws IOException  {
         final String[] methods = { "POST", "PUT", "GET", "DELETE" };
 
-        try (final RestClient restClient = createRestClient(true, false)) {
+        try (RestClient restClient = createRestClient(true, false)) {
             for (final String method : methods) {
                 final Response response = bodyTest(restClient, method);
 

core/src/main/java/org/apache/lucene/search/grouping/CollapseTopFieldDocs.java

@@ -56,7 +56,7 @@ private static class ShardRef {
         // Which hit within the shard:
         int hitIndex;
 
-        public ShardRef(int shardIndex) {
+        ShardRef(int shardIndex) {
             this.shardIndex = shardIndex;
         }
 
@@ -72,7 +72,7 @@ private static class MergeSortQueue extends PriorityQueue<ShardRef> {
         final FieldComparator<?>[] comparators;
         final int[] reverseMul;
 
-        public MergeSortQueue(Sort sort, CollapseTopFieldDocs[] shardHits) throws IOException {
+        MergeSortQueue(Sort sort, CollapseTopFieldDocs[] shardHits) throws IOException {
             super(shardHits.length);
             this.shardHits = new ScoreDoc[shardHits.length][];
             for (int shardIDX = 0; shardIDX < shardHits.length; shardIDX++) {

core/src/main/java/org/apache/lucene/search/grouping/CollapsingDocValuesSource.java

@@ -56,7 +56,7 @@ static class Numeric extends CollapsingDocValuesSource<Long> {
         private NumericDocValues values;
         private Bits docsWithField;
 
-        public Numeric(String field) throws IOException {
+        Numeric(String field) throws IOException {
             super(field);
         }
 
@@ -122,7 +122,7 @@ static class Keyword extends CollapsingDocValuesSource<BytesRef> {
         private Bits docsWithField;
         private SortedDocValues values;
 
-        public Keyword(String field) throws IOException {
+        Keyword(String field) throws IOException {
             super(field);
         }
 

core/src/main/java/org/apache/lucene/search/suggest/analyzing/XAnalyzingSuggester.java

@@ -392,7 +392,7 @@ private static final class  EscapingTokenStreamToAutomaton extends TokenStreamTo
     final BytesRefBuilder spare = new BytesRefBuilder();
     private char sepLabel;
 
-    public EscapingTokenStreamToAutomaton(char sepLabel) {
+    EscapingTokenStreamToAutomaton(char sepLabel) {
       this.sepLabel = sepLabel;
     }
 
@@ -432,7 +432,7 @@ private static class AnalyzingComparator implements Comparator<BytesRef> {
 
     private final boolean hasPayloads;
 
-    public AnalyzingComparator(boolean hasPayloads) {
+    AnalyzingComparator(boolean hasPayloads) {
       this.hasPayloads = hasPayloads;
     }
 
@@ -1114,7 +1114,7 @@ private static final class SurfaceFormAndPayload implements Comparable<SurfaceFo
             BytesRef payload;
             long weight;
 
-            public SurfaceFormAndPayload(BytesRef payload, long cost) {
+            SurfaceFormAndPayload(BytesRef payload, long cost) {
                 super();
                 this.payload = payload;
                 this.weight = cost;

core/src/main/java/org/elasticsearch/ExceptionsHelper.java

@@ -214,7 +214,7 @@ static class GroupBy {
         final String index;
         final Class<? extends Throwable> causeType;
 
-        public GroupBy(Throwable t) {
+        GroupBy(Throwable t) {
             if (t instanceof ElasticsearchException) {
                 final Index index = ((ElasticsearchException) t).getIndex();
                 if (index != null) {

core/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -383,7 +383,7 @@ public ActionModule(boolean transportClient, Settings settings, IndexNameExpress
     static Map<String, ActionHandler<?, ?>> setupActions(List<ActionPlugin> actionPlugins) {
         // Subclass NamedRegistry for easy registration
         class ActionRegistry extends NamedRegistry<ActionHandler<?, ?>> {
-            public ActionRegistry() {
+            ActionRegistry() {
                 super("action");
             }
 

core/src/main/java/org/elasticsearch/action/ListenableActionFuture.java

@@ -29,5 +29,5 @@ public interface ListenableActionFuture<T> extends ActionFuture<T> {
     /**
      * Add an action listener to be invoked when a response has received.
      */
-    void addListener(final ActionListener<T> listener);
+    void addListener(ActionListener<T> listener);
 }

core/src/main/java/org/elasticsearch/action/admin/cluster/node/tasks/cancel/TransportCancelTasksAction.java

@@ -217,7 +217,7 @@ private static class BanLock {
         private final AtomicInteger counter;
         private final int nodesSize;
 
-        public BanLock(int nodesSize, Runnable finish) {
+        BanLock(int nodesSize, Runnable finish) {
             counter = new AtomicInteger(0);
             this.finish = finish;
             this.nodesSize = nodesSize;
@@ -268,7 +268,7 @@ private BanParentTaskRequest(TaskId parentTaskId) {
             this.ban = false;
         }
 
-        public BanParentTaskRequest() {
+        BanParentTaskRequest() {
         }
 
         @Override

core/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/status/SnapshotIndexShardStage.java

@@ -49,7 +49,7 @@ public enum SnapshotIndexShardStage {
 
     private boolean completed;
 
-    private SnapshotIndexShardStage(byte value, boolean completed) {
+    SnapshotIndexShardStage(byte value, boolean completed) {
         this.value = value;
         this.completed = completed;
     }

core/src/main/java/org/elasticsearch/action/admin/indices/get/GetIndexRequest.java

@@ -34,7 +34,7 @@
  */
 public class GetIndexRequest extends ClusterInfoRequest<GetIndexRequest> {
 
-    public static enum Feature {
+    public enum Feature {
         ALIASES((byte) 0, "_aliases", "_alias"),
         MAPPINGS((byte) 1, "_mappings", "_mapping"),
         SETTINGS((byte) 2, "_settings");
@@ -52,7 +52,7 @@ public static enum Feature {
         private final String preferredName;
         private final byte id;
 
-        private Feature(byte id, String... validNames) {
+        Feature(byte id, String... validNames) {
             assert validNames != null && validNames.length > 0;
             this.id = id;
             this.validNames = Arrays.asList(validNames);

core/src/main/java/org/elasticsearch/action/admin/indices/rollover/Condition.java

@@ -47,7 +47,7 @@ protected Condition(String name) {
         this.name = name;
     }
 
-    public abstract Result evaluate(final Stats stats);
+    public abstract Result evaluate(Stats stats);
 
     @Override
     public final String toString() {

core/src/main/java/org/elasticsearch/action/admin/indices/shards/TransportIndicesShardStoresAction.java

@@ -226,7 +226,7 @@ public class Response {
                 private final List<NodeGatewayStartedShards> responses;
                 private final List<FailedNodeException> failures;
 
-                public Response(ShardId shardId, List<NodeGatewayStartedShards> responses, List<FailedNodeException> failures) {
+                Response(ShardId shardId, List<NodeGatewayStartedShards> responses, List<FailedNodeException> failures) {
                     this.shardId = shardId;
                     this.responses = responses;
                     this.failures = failures;

core/src/main/java/org/elasticsearch/action/bulk/BackoffPolicy.java

@@ -171,7 +171,7 @@ private static final class ConstantBackoff extends BackoffPolicy {
 
         private final int numberOfElements;
 
-        public ConstantBackoff(TimeValue delay, int numberOfElements) {
+        ConstantBackoff(TimeValue delay, int numberOfElements) {
             assert numberOfElements >= 0;
             this.delay = delay;
             this.numberOfElements = numberOfElements;
@@ -188,7 +188,7 @@ private static final class ConstantBackoffIterator implements Iterator<TimeValue
         private final int numberOfElements;
         private int curr;
 
-        public ConstantBackoffIterator(TimeValue delay, int numberOfElements) {
+        ConstantBackoffIterator(TimeValue delay, int numberOfElements) {
             this.delay = delay;
             this.numberOfElements = numberOfElements;
         }
@@ -212,7 +212,7 @@ private static final class WrappedBackoffPolicy extends BackoffPolicy {
         private final BackoffPolicy delegate;
         private final Runnable onBackoff;
 
-        public WrappedBackoffPolicy(BackoffPolicy delegate, Runnable onBackoff) {
+        WrappedBackoffPolicy(BackoffPolicy delegate, Runnable onBackoff) {
             this.delegate = delegate;
             this.onBackoff = onBackoff;
         }
@@ -227,7 +227,7 @@ private static final class WrappedBackoffIterator implements Iterator<TimeValue>
         private final Iterator<TimeValue> delegate;
         private final Runnable onBackoff;
 
-        public WrappedBackoffIterator(Iterator<TimeValue> delegate, Runnable onBackoff) {
+        WrappedBackoffIterator(Iterator<TimeValue> delegate, Runnable onBackoff) {
             this.delegate = delegate;
             this.onBackoff = onBackoff;
         }

core/src/main/java/org/elasticsearch/action/bulk/BulkRequestHandler.java

@@ -59,7 +59,7 @@ private static class SyncBulkRequestHandler extends BulkRequestHandler {
         private final BulkProcessor.Listener listener;
         private final BackoffPolicy backoffPolicy;
 
-        public SyncBulkRequestHandler(Client client, BackoffPolicy backoffPolicy, BulkProcessor.Listener listener) {
+        SyncBulkRequestHandler(Client client, BackoffPolicy backoffPolicy, BulkProcessor.Listener listener) {
             super(client);
             this.backoffPolicy = backoffPolicy;
             this.listener = listener;

core/src/main/java/org/elasticsearch/action/bulk/Retry.java

@@ -102,7 +102,7 @@ static class AbstractRetryHandler implements ActionListener<BulkResponse> {
         private volatile BulkRequest currentBulkRequest;
         private volatile ScheduledFuture<?> scheduledRequestFuture;
 
-        public AbstractRetryHandler(Class<? extends Throwable> retryOnThrowable, BackoffPolicy backoffPolicy, Client client, ActionListener<BulkResponse> listener) {
+        AbstractRetryHandler(Class<? extends Throwable> retryOnThrowable, BackoffPolicy backoffPolicy, Client client, ActionListener<BulkResponse> listener) {
             this.retryOnThrowable = retryOnThrowable;
             this.backoff = backoffPolicy.iterator();
             this.client = client;
@@ -213,7 +213,7 @@ public void execute(BulkRequest bulkRequest) {
     }
 
     static class AsyncRetryHandler extends AbstractRetryHandler {
-        public AsyncRetryHandler(Class<? extends Throwable> retryOnThrowable, BackoffPolicy backoffPolicy, Client client, ActionListener<BulkResponse> listener) {
+        AsyncRetryHandler(Class<? extends Throwable> retryOnThrowable, BackoffPolicy backoffPolicy, Client client, ActionListener<BulkResponse> listener) {
             super(retryOnThrowable, backoffPolicy, client, listener);
         }
     }
@@ -226,7 +226,7 @@ public static SyncRetryHandler create(Class<? extends Throwable> retryOnThrowabl
             return new SyncRetryHandler(retryOnThrowable, backoffPolicy, client, actionFuture);
         }
 
-        public SyncRetryHandler(Class<? extends Throwable> retryOnThrowable, BackoffPolicy backoffPolicy, Client client, PlainActionFuture<BulkResponse> actionFuture) {
+        SyncRetryHandler(Class<? extends Throwable> retryOnThrowable, BackoffPolicy backoffPolicy, Client client, PlainActionFuture<BulkResponse> actionFuture) {
             super(retryOnThrowable, backoffPolicy, client, actionFuture);
             this.actionFuture = actionFuture;
         }

core/src/main/java/org/elasticsearch/action/bulk/byscroll/WorkingBulkByScrollTask.java

@@ -306,7 +306,7 @@ private static class RunOnce extends AbstractRunnable {
         private final AtomicBoolean hasRun = new AtomicBoolean(false);
         private final AbstractRunnable delegate;
 
-        public RunOnce(AbstractRunnable delegate) {
+        RunOnce(AbstractRunnable delegate) {
             this.delegate = delegate;
         }
 

core/src/main/java/org/elasticsearch/action/search/AbstractSearchAsyncAction.java

@@ -429,7 +429,7 @@ final class FetchPhase implements CheckedRunnable<Exception> {
         private final SearchPhaseController searchPhaseController;
         private final AtomicArray<QuerySearchResultProvider> queryResults;
 
-        public FetchPhase(AtomicArray<QuerySearchResultProvider> queryResults,
+        FetchPhase(AtomicArray<QuerySearchResultProvider> queryResults,
                            SearchPhaseController searchPhaseController) {
             this.fetchResults = new AtomicArray<>(queryResults.length());
             this.searchPhaseController = searchPhaseController;

core/src/main/java/org/elasticsearch/action/search/ParsedScrollId.java

@@ -34,7 +34,7 @@ class ParsedScrollId {
 
     private final ScrollIdForNode[] context;
 
-    public ParsedScrollId(String source, String type, ScrollIdForNode[] context) {
+    ParsedScrollId(String source, String type, ScrollIdForNode[] context) {
         this.source = source;
         this.type = type;
         this.context = context;

core/src/main/java/org/elasticsearch/action/search/ScrollIdForNode.java

@@ -23,7 +23,7 @@ class ScrollIdForNode {
     private final String node;
     private final long scrollId;
 
-    public ScrollIdForNode(String node, long scrollId) {
+    ScrollIdForNode(String node, long scrollId) {
         this.node = node;
         this.scrollId = scrollId;
     }

core/src/main/java/org/elasticsearch/action/search/SearchDfsQueryThenFetchAsyncAction.java

@@ -74,7 +74,7 @@ private final class DfsQueryPhase implements CheckedRunnable<Exception> {
         private final AtomicArray<DfsSearchResult> firstResults;
         private final Function<AtomicArray<QuerySearchResultProvider>, CheckedRunnable<Exception>> nextPhaseFactory;
 
-        public DfsQueryPhase(AtomicArray<DfsSearchResult> firstResults,
+        DfsQueryPhase(AtomicArray<DfsSearchResult> firstResults,
                              SearchPhaseController searchPhaseController,
                              Function<AtomicArray<QuerySearchResultProvider>, CheckedRunnable<Exception>> nextPhaseFactory) {
             this.queryResult = new AtomicArray<>(firstResults.length());

core/src/main/java/org/elasticsearch/action/search/SearchTransportService.java

@@ -197,7 +197,7 @@ public void writeTo(StreamOutput out) throws IOException {
     static class SearchFreeContextRequest extends ScrollFreeContextRequest implements IndicesRequest {
         private OriginalIndices originalIndices;
 
-        public SearchFreeContextRequest() {
+        SearchFreeContextRequest() {
         }
 
         SearchFreeContextRequest(SearchRequest request, long id) {

core/src/main/java/org/elasticsearch/action/support/ActionFilter.java

@@ -47,7 +47,7 @@ <Request extends ActionRequest, Response extends ActionResponse> void apply(Task
      * filter chain. This base class should serve any action filter implementations that doesn't require
      * to apply async filtering logic.
      */
-    public abstract static class Simple extends AbstractComponent implements ActionFilter {
+    abstract class Simple extends AbstractComponent implements ActionFilter {
 
         protected Simple(Settings settings) {
             super(settings);

core/src/main/java/org/elasticsearch/action/support/ActionFilterChain.java

@@ -33,5 +33,5 @@ public interface ActionFilterChain<Request extends ActionRequest, Response exten
      * Continue processing the request. Should only be called if a response has not been sent through
      * the given {@link ActionListener listener}
      */
-    void proceed(Task task, final String action, final Request request, final ActionListener<Response> listener);
+    void proceed(Task task, String action, Request request, ActionListener<Response> listener);
 }

core/src/main/java/org/elasticsearch/action/support/broadcast/node/TransportBroadcastByNodeAction.java

@@ -522,10 +522,10 @@ class NodeResponse extends TransportResponse {
         protected List<BroadcastShardOperationFailedException> exceptions;
         protected List<ShardOperationResult> results;
 
-        public NodeResponse() {
+        NodeResponse() {
         }
 
-        public NodeResponse(String nodeId,
+        NodeResponse(String nodeId,
                             int totalShards,
                             List<ShardOperationResult> results,
                             List<BroadcastShardOperationFailedException> exceptions) {