[prone] Add UnusedMethod

Signed-off-by: Vincent Potucek <vpotucek@me.com>

Author: Vincent Potucek

CHANGELOG.md

@@ -20,6 +20,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add build-tooling to run in FIPS environment ([#18921](https://github.com/opensearch-project/OpenSearch/pull/18921))
 - Add SMILE/CBOR/YAML document format support to Bulk GRPC endpoint ([#19744](https://github.com/opensearch-project/OpenSearch/pull/19744))
 - Implement GRPC ConstantScoreQuery, FuzzyQuery, MatchBoolPrefixQuery, MatchPhrasePrefix, PrefixQuery, MatchQuery ([#19854](https://github.com/opensearch-project/OpenSearch/pull/19854))
+- [prone] Add `UnusedMethod` ([#19896](https://github.com/opensearch-project/OpenSearch/pull/19896))
 
 ### Changed
 - Faster `terms` query creation for `keyword` field with index and docValues enabled ([#19350](https://github.com/opensearch-project/OpenSearch/pull/19350))

build.gradle

@@ -59,6 +59,7 @@ plugins {
   id "org.gradle.test-retry" version "1.6.2" apply false
   id "test-report-aggregation"
   id 'jacoco-report-aggregation'
+  id 'net.ltgt.errorprone' version '4.3.0' apply false
 }
 
 apply from: 'gradle/build-complete.gradle'
@@ -71,13 +72,10 @@ apply from: 'gradle/run.gradle'
 apply from: 'gradle/missing-javadoc.gradle'
 apply from: 'gradle/code-coverage.gradle'
 
-// Apply FIPS configuration to all projects
 allprojects {
+  apply from: "$rootDir/gradle/error-prone.gradle"
   apply from: "$rootDir/gradle/fips.gradle"
-}
-
-// common maven publishing configuration
-allprojects {
+  // common maven publishing configuration
   group = 'org.opensearch'
   version = VersionProperties.getOpenSearch()
   description = "OpenSearch subproject ${project.path}"

gradle/error-prone.gradle

@@ -0,0 +1,50 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+apply plugin: 'net.ltgt.errorprone'
+
+tasks.withType(JavaCompile).configureEach {
+  options.errorprone {
+    disableAllChecks = true // remove once complain
+    error(
+      'UnusedMethod'
+    )
+    errorproneArgs.add(
+      '-XepExcludedPaths:' +
+      '.*AggregatorTestCase.java|' + // https://github.com/google/error-prone/issues/5289
+      '.*FactoryProvider.java|' +
+      '.*IT.java|' + // 6+ findings
+      '.*MockBigArrays.java|' +
+      '.*MoreTypes.java|' +
+      '.*OpenSearchNode.java|' +
+      '.*SnapshotsService.java|' +
+      '.*Terms.java|' +
+      '.*Tests.java|' + // 15+ findings
+      '.*x-content.*' // generated code
+    )
+  }
+}
+
+dependencies {
+  errorprone('com.google.errorprone:error_prone_core:2.42.0')
+  errorprone('tech.picnic.error-prone-support:error-prone-contrib:0.25.0')
+}
+
+configurations.configureEach { // remove once in sync (collision resolved)
+  resolutionStrategy {
+    force 'com.google.code.findbugs:jsr305:3.0.2'
+    force 'com.google.errorprone:error_prone_annotations:2.42.0'
+    force 'com.google.errorprone:error_prone_core:2.42.0'
+    force 'com.google.guava:guava:33.4.0-jre'
+    force 'org.checkerframework:checker-qual:3.43.0'
+  }
+}
+
+repositories {
+  mavenCentral()
+}

server/src/main/java/org/opensearch/action/support/broadcast/node/TransportBroadcastByNodeAction.java

@@ -687,8 +687,6 @@ public static final class EmptyResult implements Writeable {
 
         private EmptyResult() {}
 
-        private EmptyResult(StreamInput in) {}
-
         @Override
         public void writeTo(StreamOutput out) {}
 

server/src/main/java/org/opensearch/action/support/tasks/TransportTasksAction.java

@@ -440,14 +440,6 @@ private class NodeTasksResponse extends TransportResponse {
             this.exceptions = exceptions;
         }
 
-        public String getNodeId() {
-            return nodeId;
-        }
-
-        public List<TaskOperationFailure> getExceptions() {
-            return exceptions;
-        }
-
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             out.writeString(nodeId);

server/src/main/java/org/opensearch/common/inject/matcher/Matchers.java

@@ -29,8 +29,6 @@
 
 package org.opensearch.common.inject.matcher;
 
-import org.opensearch.common.SuppressForbidden;
-
 import java.lang.annotation.Annotation;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -72,10 +70,6 @@ public boolean matches(Object o) {
         public String toString() {
             return "any()";
         }
-
-        public Object readResolve() {
-            return any();
-        }
     }
 
     /**
@@ -372,12 +366,6 @@ public int hashCode() {
         public String toString() {
             return "inPackage(" + targetPackage.getName() + ")";
         }
-
-        @SuppressForbidden(reason = "ClassLoader.getDefinedPackage not available yet")
-        public Object readResolve() {
-            // TODO minJava >= 9 : use ClassLoader.getDefinedPackage and remove @SuppressForbidden
-            return inPackage(Package.getPackage(packageName));
-        }
     }
 
     /**

server/src/main/java/org/opensearch/common/inject/spi/InjectionPoint.java

@@ -76,12 +76,6 @@ public final class InjectionPoint {
     private final Member member;
     private final List<Dependency<?>> dependencies;
 
-    private InjectionPoint(Member member, List<Dependency<?>> dependencies, boolean optional) {
-        this.member = member;
-        this.dependencies = dependencies;
-        this.optional = optional;
-    }
-
     InjectionPoint(TypeLiteral<?> type, Method method) {
         this.member = method;
 

server/src/main/java/org/opensearch/common/time/JavaDateFormatter.java

@@ -245,15 +245,6 @@ private JavaDateFormatter(
         this.canCacheLastParsedFormatter = canCacheLastParsedFormatter;
     }
 
-    private JavaDateFormatter(
-        String format,
-        DateTimeFormatter printer,
-        List<DateTimeFormatter> roundUpParsers,
-        List<DateTimeFormatter> parsers
-    ) {
-        this(format, format, wrapFormatter(printer), wrapAllFormatters(roundUpParsers), wrapAllFormatters(parsers), false);
-    }
-
     private JavaDateFormatter(
         String format,
         OpenSearchDateTimePrinter printer,

server/src/main/java/org/opensearch/gateway/GatewayMetaState.java

@@ -38,10 +38,8 @@
 import org.opensearch.ExceptionsHelper;
 import org.opensearch.OpenSearchException;
 import org.opensearch.Version;
-import org.opensearch.cluster.ClusterChangedEvent;
 import org.opensearch.cluster.ClusterName;
 import org.opensearch.cluster.ClusterState;
-import org.opensearch.cluster.ClusterStateApplier;
 import org.opensearch.cluster.coordination.CoordinationMetadata;
 import org.opensearch.cluster.coordination.CoordinationState.PersistedState;
 import org.opensearch.cluster.coordination.InMemoryPersistedState;
@@ -379,40 +377,6 @@ private static boolean applyPluginUpgraders(
         return false;
     }
 
-    private static class GatewayClusterApplier implements ClusterStateApplier {
-
-        private static final Logger logger = LogManager.getLogger(GatewayClusterApplier.class);
-
-        private final IncrementalClusterStateWriter incrementalClusterStateWriter;
-
-        private GatewayClusterApplier(IncrementalClusterStateWriter incrementalClusterStateWriter) {
-            this.incrementalClusterStateWriter = incrementalClusterStateWriter;
-        }
-
-        @Override
-        public void applyClusterState(ClusterChangedEvent event) {
-            if (event.state().blocks().disableStatePersistence()) {
-                incrementalClusterStateWriter.setIncrementalWrite(false);
-                return;
-            }
-
-            try {
-                // Hack: This is to ensure that non-cluster-manager-eligible Zen2 nodes always store a current term
-                // that's higher than the last accepted term.
-                // TODO: can we get rid of this hack?
-                if (event.state().term() > incrementalClusterStateWriter.getPreviousManifest().getCurrentTerm()) {
-                    incrementalClusterStateWriter.setCurrentTerm(event.state().term());
-                }
-
-                incrementalClusterStateWriter.updateClusterState(event.state());
-                incrementalClusterStateWriter.setIncrementalWrite(true);
-            } catch (WriteStateException e) {
-                logger.warn("Exception occurred when storing new meta data", e);
-            }
-        }
-
-    }
-
     @Override
     public void close() throws IOException {
         IOUtils.close(persistedStateRegistry);

server/src/main/java/org/opensearch/indices/replication/common/ReplicationLuceneIndex.java

@@ -374,10 +374,6 @@ public int size() {
             return fileMetadataMap.size();
         }
 
-        public boolean isEmpty() {
-            return fileMetadataMap.isEmpty();
-        }
-
         public void clear() {
             fileMetadataMap.clear();
             complete = false;