diff --git a/build-tools-internal/src/main/resources/checkstyle.xml b/build-tools-internal/src/main/resources/checkstyle.xml
index e0db1be76d96..95a32e026c1f 100644
--- a/build-tools-internal/src/main/resources/checkstyle.xml
+++ b/build-tools-internal/src/main/resources/checkstyle.xml
@@ -107,6 +107,13 @@
 
     <!-- Checks that a local variable or a parameter does not shadow a field that is defined in the same class. -->
     <!-- Use a forked version that understands setters that don't start with "set". -->
+    <!-- Notes on `ignoredMethodNames`:
+
+        * `createParser` creates objects so should be considered a sort-of constructor
+        * `createComponents` by its nature ends up referring to fields
+          a lot, and there's no benefit to flagging shadowed variables in
+          those methods.
+    -->
     <!-- Disabled until existing violations are fixed -->
     <!--
     <module name="org.elasticsearch.gradle.internal.checkstyle.HiddenFieldCheck">
@@ -117,7 +124,7 @@
         <property name="minLineCount" value="5" />
         <property name="ignoreFormat" value="^(?:threadPool)$"/>
         <property name="ignoreAbstractMethods" value="true"/>
-        <property name="ignoreMethodNames" value="^(?:createParser)$"/>
+        <property name="ignoreMethodNames" value="^(?:createParser|createComponents)$"/>
         <property name="setterCanReturnItsClass" value="true"/>
         <message key="hidden.field" value="''{0}'' hides a field." />
     </module>
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java
index 6d950d7e4bf4..6e01d394999a 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java
@@ -1114,7 +1114,7 @@ public class MachineLearning extends Plugin
 
     @Override
     public List<RestHandler> getRestHandlers(
-        Settings settings,
+        Settings unused,
         RestController restController,
         ClusterSettings clusterSettings,
         IndexScopedSettings indexScopedSettings,
@@ -1306,7 +1306,7 @@ public class MachineLearning extends Plugin
     }
 
     @Override
-    public List<ExecutorBuilder<?>> getExecutorBuilders(Settings settings) {
+    public List<ExecutorBuilder<?>> getExecutorBuilders(Settings unused) {
         if (false == enabled) {
             return emptyList();
         }
@@ -1496,7 +1496,7 @@ public class MachineLearning extends Plugin
     }
 
     @Override
-    public Collection<SystemIndexDescriptor> getSystemIndexDescriptors(Settings settings) {
+    public Collection<SystemIndexDescriptor> getSystemIndexDescriptors(Settings unused) {
         return List.of(
             SystemIndexDescriptor.builder()
                 .setIndexPattern(MlMetaIndex.indexName() + "*")
@@ -1799,7 +1799,7 @@ public class MachineLearning extends Plugin
     }
 
     @Override
-    public BreakerSettings getCircuitBreaker(Settings settings) {
+    public BreakerSettings getCircuitBreaker(Settings settingsToUse) {
         return BreakerSettings.updateFromSettings(
             new BreakerSettings(
                 TRAINED_MODEL_CIRCUIT_BREAKER_NAME,
@@ -1808,7 +1808,7 @@ public class MachineLearning extends Plugin
                 CircuitBreaker.Type.MEMORY,
                 CircuitBreaker.Durability.TRANSIENT
             ),
-            settings
+            settingsToUse
         );
     }
 
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MlInitializationService.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MlInitializationService.java
index 72223869a490..dc32b4e4ded1 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MlInitializationService.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MlInitializationService.java
@@ -179,7 +179,7 @@ public class MlInitializationService implements ClusterStateListener {
 
         // The atomic flag shortcircuits the check after no legacy templates have been found to exist.
         if (this.isMaster && checkForLegacyMlTemplates.get()) {
-            if (deleteOneMlLegacyTemplateIfNecessary(client, event.state()) == false) {
+            if (deleteOneMlLegacyTemplateIfNecessary(event.state()) == false) {
                 checkForLegacyMlTemplates.set(false);
             }
         }
@@ -189,7 +189,7 @@ public class MlInitializationService implements ClusterStateListener {
      * @return <code>true</code> if further calls to this method are worthwhile.
      *         <code>false</code> if this method never needs to be called again.
      */
-    private boolean deleteOneMlLegacyTemplateIfNecessary(Client client, ClusterState state) {
+    private boolean deleteOneMlLegacyTemplateIfNecessary(ClusterState state) {
 
         String templateToDelete = nextTemplateToDelete(state.getMetadata().getTemplates());
         if (templateToDelete != null) {
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportDeleteExpiredDataAction.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportDeleteExpiredDataAction.java
index 7a5b6ff47e4c..e4a07d925593 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportDeleteExpiredDataAction.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportDeleteExpiredDataAction.java
@@ -132,10 +132,10 @@ public class TransportDeleteExpiredDataAction extends HandledTransportAction<
         TaskId taskId = new TaskId(clusterService.localNode().getId(), task.getId());
 
         BooleanSupplier isTimedOutSupplier = () -> Instant.now(clock).isAfter(timeoutTime);
-        AnomalyDetectionAuditor auditor = new AnomalyDetectionAuditor(client, clusterService);
+        AnomalyDetectionAuditor anomalyDetectionAuditor = new AnomalyDetectionAuditor(client, clusterService);
 
         if (Strings.isNullOrEmpty(request.getJobId()) || Strings.isAllOrWildcard(request.getJobId())) {
-            List<MlDataRemover> dataRemovers = createDataRemovers(client, taskId, auditor);
+            List<MlDataRemover> dataRemovers = createDataRemovers(client, taskId, anomalyDetectionAuditor);
             threadPool.executor(MachineLearning.UTILITY_THREAD_POOL_NAME)
                 .execute(() -> deleteExpiredData(request, dataRemovers, listener, isTimedOutSupplier));
         } else {
@@ -144,7 +144,7 @@ public class TransportDeleteExpiredDataAction extends HandledTransportAction<
                     List<Job> jobs = jobBuilders.stream().map(Job.Builder::build).collect(Collectors.toList());
                     String[] jobIds = jobs.stream().map(Job::getId).toArray(String[]::new);
                     request.setExpandedJobIds(jobIds);
-                    List<MlDataRemover> dataRemovers = createDataRemovers(jobs, taskId, auditor);
+                    List<MlDataRemover> dataRemovers = createDataRemovers(jobs, taskId, anomalyDetectionAuditor);
                     deleteExpiredData(request, dataRemovers, listener, isTimedOutSupplier);
                 });
             }, listener::onFailure));
@@ -232,40 +232,44 @@ public class TransportDeleteExpiredDataAction extends HandledTransportAction<
         }
     }
 
-    private List<MlDataRemover> createDataRemovers(OriginSettingClient client, TaskId parentTaskId, AnomalyDetectionAuditor auditor) {
+    private List<MlDataRemover> createDataRemovers(
+        OriginSettingClient originClient,
+        TaskId parentTaskId,
+        AnomalyDetectionAuditor anomalyDetectionAuditor
+    ) {
         return Arrays.asList(
             new ExpiredResultsRemover(
-                client,
-                new WrappedBatchedJobsIterator(new SearchAfterJobsIterator(client)),
+                originClient,
+                new WrappedBatchedJobsIterator(new SearchAfterJobsIterator(originClient)),
                 parentTaskId,
-                auditor,
+                anomalyDetectionAuditor,
                 threadPool
             ),
-            new ExpiredForecastsRemover(client, threadPool, parentTaskId),
+            new ExpiredForecastsRemover(originClient, threadPool, parentTaskId),
             new ExpiredModelSnapshotsRemover(
-                client,
-                new WrappedBatchedJobsIterator(new SearchAfterJobsIterator(client)),
+                originClient,
+                new WrappedBatchedJobsIterator(new SearchAfterJobsIterator(originClient)),
                 threadPool,
                 parentTaskId,
                 jobResultsProvider,
-                auditor
+                anomalyDetectionAuditor
             ),
-            new UnusedStateRemover(client, parentTaskId),
-            new EmptyStateIndexRemover(client, parentTaskId),
-            new UnusedStatsRemover(client, parentTaskId),
+            new UnusedStateRemover(originClient, parentTaskId),
+            new EmptyStateIndexRemover(originClient, parentTaskId),
+            new UnusedStatsRemover(originClient, parentTaskId),
             new ExpiredAnnotationsRemover(
-                client,
-                new WrappedBatchedJobsIterator(new SearchAfterJobsIterator(client)),
+                originClient,
+                new WrappedBatchedJobsIterator(new SearchAfterJobsIterator(originClient)),
                 parentTaskId,
-                auditor,
+                anomalyDetectionAuditor,
                 threadPool
             )
         );
     }
 
-    private List<MlDataRemover> createDataRemovers(List<Job> jobs, TaskId parentTaskId, AnomalyDetectionAuditor auditor) {
+    private List<MlDataRemover> createDataRemovers(List<Job> jobs, TaskId parentTaskId, AnomalyDetectionAuditor anomalyDetectionAuditor) {
         return Arrays.asList(
-            new ExpiredResultsRemover(client, new VolatileCursorIterator<>(jobs), parentTaskId, auditor, threadPool),
+            new ExpiredResultsRemover(client, new VolatileCursorIterator<>(jobs), parentTaskId, anomalyDetectionAuditor, threadPool),
             new ExpiredForecastsRemover(client, threadPool, parentTaskId),
             new ExpiredModelSnapshotsRemover(
                 client,
@@ -273,12 +277,12 @@ public class TransportDeleteExpiredDataAction extends HandledTransportAction<
                 threadPool,
                 parentTaskId,
                 jobResultsProvider,
-                auditor
+                anomalyDetectionAuditor
             ),
             new UnusedStateRemover(client, parentTaskId),
             new EmptyStateIndexRemover(client, parentTaskId),
             new UnusedStatsRemover(client, parentTaskId),
-            new ExpiredAnnotationsRemover(client, new VolatileCursorIterator<>(jobs), parentTaskId, auditor, threadPool)
+            new ExpiredAnnotationsRemover(client, new VolatileCursorIterator<>(jobs), parentTaskId, anomalyDetectionAuditor, threadPool)
         );
     }
 
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDataFrameAnalyticsAction.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDataFrameAnalyticsAction.java
index 023092cecf7b..589a9a9a34ac 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDataFrameAnalyticsAction.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDataFrameAnalyticsAction.java
@@ -699,7 +699,7 @@ public class TransportStartDataFrameAnalyticsAction extends TransportMasterNodeA
         public PersistentTasksCustomMetadata.Assignment getAssignment(
             TaskParams params,
             Collection<DiscoveryNode> candidateNodes,
-            ClusterState clusterState
+            @SuppressWarnings("HiddenField") ClusterState clusterState
         ) {
             boolean isMemoryTrackerRecentlyRefreshed = memoryTracker.isRecentlyRefreshed();
             Optional<PersistentTasksCustomMetadata.Assignment> optionalAssignment = getPotentialAssignment(
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/CategorizeTextAggregatorFactory.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/CategorizeTextAggregatorFactory.java
index 24d22d22fd78..ca56741796ae 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/CategorizeTextAggregatorFactory.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/CategorizeTextAggregatorFactory.java
@@ -97,15 +97,15 @@ public class CategorizeTextAggregatorFactory extends AggregatorFactory {
                     + "]"
             );
         }
-        TermsAggregator.BucketCountThresholds bucketCountThresholds = new TermsAggregator.BucketCountThresholds(this.bucketCountThresholds);
-        if (bucketCountThresholds.getShardSize() == CategorizeTextAggregationBuilder.DEFAULT_BUCKET_COUNT_THRESHOLDS.getShardSize()) {
+        TermsAggregator.BucketCountThresholds thresholds = new TermsAggregator.BucketCountThresholds(this.bucketCountThresholds);
+        if (thresholds.getShardSize() == CategorizeTextAggregationBuilder.DEFAULT_BUCKET_COUNT_THRESHOLDS.getShardSize()) {
             // The user has not made a shardSize selection. Use default
             // heuristic to avoid any wrong-ranking caused by distributed
             // counting
             // TODO significant text does a 2x here, should we as well?
-            bucketCountThresholds.setShardSize(BucketUtils.suggestShardSideQueueSize(bucketCountThresholds.getRequiredSize()));
+            thresholds.setShardSize(BucketUtils.suggestShardSideQueueSize(thresholds.getRequiredSize()));
         }
-        bucketCountThresholds.ensureValidity();
+        thresholds.ensureValidity();
 
         return new CategorizeTextAggregator(
             name,
@@ -114,7 +114,7 @@ public class CategorizeTextAggregatorFactory extends AggregatorFactory {
             parent,
             indexedFieldName,
             fieldType,
-            bucketCountThresholds,
+            thresholds,
             maxUniqueTokens,
             maxMatchTokens,
             similarityThreshold,
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/InternalCategorizationAggregation.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/InternalCategorizationAggregation.java
index 63ccda95b4c3..f9d653d0abf9 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/InternalCategorizationAggregation.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/categorization/InternalCategorizationAggregation.java
@@ -53,14 +53,14 @@ public class InternalCategorizationAggregation extends InternalMultiBucketAggreg
             return docCount;
         }
 
-        public Bucket reduce(BucketKey key, ReduceContext reduceContext) {
+        public Bucket reduce(BucketKey bucketKey, ReduceContext reduceContext) {
             List<InternalAggregations> innerAggs = new ArrayList<>(toReduce.size());
-            long docCount = 0;
+            long totalDocCount = 0;
             for (Bucket bucket : toReduce) {
                 innerAggs.add(bucket.aggregations);
-                docCount += bucket.docCount;
+                totalDocCount += bucket.docCount;
             }
-            return new Bucket(key, docCount, InternalAggregations.reduce(innerAggs, reduceContext));
+            return new Bucket(bucketKey, totalDocCount, InternalAggregations.reduce(innerAggs, reduceContext));
         }
 
         public DelayedCategorizationBucket add(Bucket bucket) {
@@ -316,7 +316,7 @@ public class InternalCategorizationAggregation extends InternalMultiBucketAggreg
     }
 
     @Override
-    public InternalCategorizationAggregation create(List<Bucket> buckets) {
+    public InternalCategorizationAggregation create(List<Bucket> bucketList) {
         return new InternalCategorizationAggregation(
             name,
             requiredSize,
@@ -325,7 +325,7 @@ public class InternalCategorizationAggregation extends InternalMultiBucketAggreg
             maxMatchTokens,
             similarityThreshold,
             super.metadata,
-            buckets
+            bucketList
         );
     }
 
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/inference/InferencePipelineAggregationBuilder.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/inference/InferencePipelineAggregationBuilder.java
index 5b40b1308b02..055a2861a473 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/inference/InferencePipelineAggregationBuilder.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/inference/InferencePipelineAggregationBuilder.java
@@ -264,10 +264,10 @@ public class InferencePipelineAggregationBuilder extends AbstractPipelineAggrega
 
         SetOnce<LocalModel> loadedModel = new SetOnce<>();
         BiConsumer<Client, ActionListener<?>> modelLoadAction = (client, listener) -> modelLoadingService.get()
-            .getModelForSearch(modelId, listener.delegateFailure((delegate, model) -> {
-                loadedModel.set(model);
+            .getModelForSearch(modelId, listener.delegateFailure((delegate, localModel) -> {
+                loadedModel.set(localModel);
 
-                boolean isLicensed = model.getLicenseLevel() == License.OperationMode.BASIC
+                boolean isLicensed = localModel.getLicenseLevel() == License.OperationMode.BASIC
                     || MachineLearningField.ML_API_FEATURE.check(licenseState);
                 if (isLicensed) {
                     delegate.onResponse(null);
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/kstest/BucketCountKSTestAggregator.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/kstest/BucketCountKSTestAggregator.java
index 9d404697028d..05293ac8c544 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/kstest/BucketCountKSTestAggregator.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/aggs/kstest/BucketCountKSTestAggregator.java
@@ -248,7 +248,7 @@ public class BucketCountKSTestAggregator extends SiblingPipelineAggregator {
             );
         }
         final MlAggsHelper.DoubleBucketValues bucketsValue = maybeBucketsValue.get();
-        double[] fractions = this.fractions == null
+        double[] fractionsArr = this.fractions == null
             ? DoubleStream.concat(
                 DoubleStream.of(0.0),
                 Stream.generate(() -> 1.0 / (bucketsValue.getDocCounts().length - 1))
@@ -258,6 +258,6 @@ public class BucketCountKSTestAggregator extends SiblingPipelineAggregator {
             // We prepend zero to the fractions as we prepend 0 to the doc counts and we want them to be the same length when
             // we create the monotonically increasing values for distribution comparison.
             : DoubleStream.concat(DoubleStream.of(0.0), Arrays.stream(this.fractions)).toArray();
-        return new InternalKSTestAggregation(name(), metadata(), ksTest(fractions, bucketsValue, alternatives, samplingMethod));
+        return new InternalKSTestAggregation(name(), metadata(), ksTest(fractionsArr, bucketsValue, alternatives, samplingMethod));
     }
 }
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/autoscaling/MlAutoscalingDeciderService.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/autoscaling/MlAutoscalingDeciderService.java
index 8498ebf0c80c..34db2e7d039d 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/autoscaling/MlAutoscalingDeciderService.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/autoscaling/MlAutoscalingDeciderService.java
@@ -604,15 +604,15 @@ public class MlAutoscalingDeciderService implements AutoscalingDeciderService, L
             if (nodeLoads.size() > 1) {
                 long totalAssignedJobs = nodeLoads.stream().mapToLong(NodeLoad::getNumAssignedJobs).sum();
                 // one volatile read
-                long maxOpenJobs = this.maxOpenJobs;
-                if (totalAssignedJobs > maxOpenJobs) {
+                long maxOpenJobsCopy = this.maxOpenJobs;
+                if (totalAssignedJobs > maxOpenJobsCopy) {
                     String msg = String.format(
                         Locale.ROOT,
                         "not scaling down as the total number of jobs [%d] exceeds the setting [%s (%d)]. "
                             + " To allow a scale down [%s] must be increased.",
                         totalAssignedJobs,
                         MAX_OPEN_JOBS_PER_NODE.getKey(),
-                        maxOpenJobs,
+                        maxOpenJobsCopy,
                         MAX_OPEN_JOBS_PER_NODE.getKey()
                     );
                     logger.info(
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractor.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractor.java
index df711b88926d..0870053d24bc 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractor.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractor.java
@@ -211,6 +211,7 @@ class ScrollDataExtractor implements DataExtractor {
         searchHasShardFailure = true;
     }
 
+    @SuppressWarnings("HiddenField")
     protected SearchResponse executeSearchScrollRequest(String scrollId) {
         return ClientHelper.executeWithHeaders(
             context.headers,
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractorFactory.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractorFactory.java
index f343389afb97..fb3c65ab6053 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractorFactory.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/extractor/scroll/ScrollDataExtractorFactory.java
@@ -77,7 +77,7 @@ public class ScrollDataExtractorFactory implements DataExtractorFactory {
         ActionListener<DataExtractorFactory> listener
     ) {
 
-        // Step 2. Contruct the factory and notify listener
+        // Step 2. Construct the factory and notify listener
         ActionListener<FieldCapabilitiesResponse> fieldCapabilitiesHandler = ActionListener.wrap(fieldCapabilitiesResponse -> {
             if (fieldCapabilitiesResponse.getIndices().length == 0) {
                 listener.onFailure(
@@ -89,10 +89,8 @@ public class ScrollDataExtractorFactory implements DataExtractorFactory {
                 );
                 return;
             }
-            TimeBasedExtractedFields extractedFields = TimeBasedExtractedFields.build(job, datafeed, fieldCapabilitiesResponse);
-            listener.onResponse(
-                new ScrollDataExtractorFactory(client, datafeed, job, extractedFields, xContentRegistry, timingStatsReporter)
-            );
+            TimeBasedExtractedFields fields = TimeBasedExtractedFields.build(job, datafeed, fieldCapabilitiesResponse);
+            listener.onResponse(new ScrollDataExtractorFactory(client, datafeed, job, fields, xContentRegistry, timingStatsReporter));
         }, e -> {
             Throwable cause = ExceptionsHelper.unwrapCause(e);
             if (cause instanceof IndexNotFoundException) {
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsManager.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsManager.java
index 2c8a72c79d6f..e74945f13c63 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsManager.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsManager.java
@@ -153,7 +153,7 @@ public class DataFrameAnalyticsManager {
     }
 
     private void createStatsIndexAndUpdateMappingsIfNecessary(
-        Client client,
+        Client clientToUse,
         ClusterState clusterState,
         TimeValue masterNodeTimeout,
         ActionListener<Boolean> listener
@@ -162,7 +162,7 @@ public class DataFrameAnalyticsManager {
             aBoolean -> ElasticsearchMappings.addDocMappingIfMissing(
                 MlStatsIndex.writeAlias(),
                 MlStatsIndex::wrappedMapping,
-                client,
+                clientToUse,
                 clusterState,
                 masterNodeTimeout,
                 listener
@@ -170,7 +170,13 @@ public class DataFrameAnalyticsManager {
             listener::onFailure
         );
 
-        MlStatsIndex.createStatsIndexAndAliasIfNecessary(client, clusterState, expressionResolver, masterNodeTimeout, createIndexListener);
+        MlStatsIndex.createStatsIndexAndAliasIfNecessary(
+            clientToUse,
+            clusterState,
+            expressionResolver,
+            masterNodeTimeout,
+            createIndexListener
+        );
     }
 
     private void determineProgressAndResume(DataFrameAnalyticsTask task, DataFrameAnalyticsConfig config) {
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsTask.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsTask.java
index f3eb9f6a954e..c01a38ab820c 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsTask.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/DataFrameAnalyticsTask.java
@@ -213,7 +213,7 @@ public class DataFrameAnalyticsTask extends LicensedAllocatedPersistentTask impl
     }
 
     // Visible for testing
-    void persistProgress(Client client, String jobId, Runnable runnable) {
+    void persistProgress(Client clientToUse, String jobId, Runnable runnable) {
         LOGGER.debug("[{}] Persisting progress", jobId);
 
         SetOnce<StoredProgress> storedProgress = new SetOnce<>();
@@ -266,7 +266,7 @@ public class DataFrameAnalyticsTask extends LicensedAllocatedPersistentTask impl
                 storedProgress.get().toXContent(jsonBuilder, Payload.XContent.EMPTY_PARAMS);
                 indexRequest.source(jsonBuilder);
             }
-            executeAsyncWithOrigin(client, ML_ORIGIN, IndexAction.INSTANCE, indexRequest, indexProgressDocListener);
+            executeAsyncWithOrigin(clientToUse, ML_ORIGIN, IndexAction.INSTANCE, indexRequest, indexProgressDocListener);
         }, e -> {
             LOGGER.error(
                 new ParameterizedMessage(
@@ -283,7 +283,7 @@ public class DataFrameAnalyticsTask extends LicensedAllocatedPersistentTask impl
             SearchRequest searchRequest = new SearchRequest(AnomalyDetectorsIndex.jobStateIndexPattern()).source(
                 new SearchSourceBuilder().size(1).query(new IdsQueryBuilder().addIds(progressDocId))
             );
-            executeAsyncWithOrigin(client, ML_ORIGIN, SearchAction.INSTANCE, searchRequest, searchFormerProgressDocListener);
+            executeAsyncWithOrigin(clientToUse, ML_ORIGIN, SearchAction.INSTANCE, searchRequest, searchFormerProgressDocListener);
         }, e -> {
             LOGGER.error(
                 new ParameterizedMessage(
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/ExtractedFieldsDetector.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/ExtractedFieldsDetector.java
index f4c0d047231f..2a62a9da6be1 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/ExtractedFieldsDetector.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/ExtractedFieldsDetector.java
@@ -82,8 +82,8 @@ public class ExtractedFieldsDetector {
         this.topNestedFieldPrefixes = findTopNestedFieldPrefixes(fieldCapabilitiesResponse);
     }
 
-    private List<String> findTopNestedFieldPrefixes(FieldCapabilitiesResponse fieldCapabilitiesResponse) {
-        List<String> sortedNestedFieldPrefixes = fieldCapabilitiesResponse.get()
+    private List<String> findTopNestedFieldPrefixes(FieldCapabilitiesResponse response) {
+        List<String> sortedNestedFieldPrefixes = response.get()
             .keySet()
             .stream()
             .filter(field -> isNested(getMappingTypes(field)))
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/process/AnalyticsProcessManager.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/process/AnalyticsProcessManager.java
index 7e797924da1a..12e13e0e4e94 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/process/AnalyticsProcessManager.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/process/AnalyticsProcessManager.java
@@ -463,9 +463,9 @@ public class AnalyticsProcessManager {
             return true;
         }
 
-        private AnalyticsProcessConfig createProcessConfig(DataFrameDataExtractor dataExtractor, ExtractedFields extractedFields) {
-            DataFrameDataExtractor.DataSummary dataSummary = dataExtractor.collectDataSummary();
-            Set<String> categoricalFields = dataExtractor.getCategoricalFields(config.getAnalysis());
+        private AnalyticsProcessConfig createProcessConfig(DataFrameDataExtractor extractor, ExtractedFields extractedFields) {
+            DataFrameDataExtractor.DataSummary dataSummary = extractor.collectDataSummary();
+            Set<String> categoricalFields = extractor.getCategoricalFields(config.getAnalysis());
             int threads = Math.min(config.getMaxNumThreads(), numAllocatedProcessors);
             return new AnalyticsProcessConfig(
                 config.getId(),
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/allocation/TrainedModelAllocationNodeService.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/allocation/TrainedModelAllocationNodeService.java
index e1e7e0424607..dd80adc9cecd 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/allocation/TrainedModelAllocationNodeService.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/allocation/TrainedModelAllocationNodeService.java
@@ -206,7 +206,7 @@ public class TrainedModelAllocationNodeService implements ClusterStateListener {
 
     public void stopDeploymentAndNotify(TrainedModelDeploymentTask task, String reason) {
         ActionListener<Void> notifyDeploymentOfStopped = ActionListener.wrap(
-            stopped -> updateStoredState(
+            _void -> updateStoredState(
                 task.getModelId(),
                 new RoutingStateAndReason(RoutingState.STOPPED, reason),
                 ActionListener.wrap(s -> {}, failure -> {})
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/DeploymentManager.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/DeploymentManager.java
index 27ecbfbe5959..76cafab1e35a 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/DeploymentManager.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/DeploymentManager.java
@@ -378,35 +378,31 @@ public class DeploymentManager {
 
         private void processResult(
             PyTorchResult pyTorchResult,
-            ProcessContext processContext,
+            ProcessContext context,
             TokenizationResult tokenization,
             NlpTask.ResultProcessor inferenceResultsProcessor,
-            ActionListener<InferenceResults> listener
+            ActionListener<InferenceResults> resultsListener
         ) {
             if (pyTorchResult.isError()) {
-                listener.onFailure(new ElasticsearchStatusException(pyTorchResult.getError(), RestStatus.INTERNAL_SERVER_ERROR));
+                resultsListener.onFailure(new ElasticsearchStatusException(pyTorchResult.getError(), RestStatus.INTERNAL_SERVER_ERROR));
                 return;
             }
 
-            logger.debug(
-                () -> new ParameterizedMessage("[{}] retrieved result for request [{}]", processContext.task.getModelId(), requestId)
-            );
+            logger.debug(() -> new ParameterizedMessage("[{}] retrieved result for request [{}]", context.task.getModelId(), requestId));
             if (notified.get()) {
                 // The request has timed out. No need to spend cycles processing the result.
                 logger.debug(
                     () -> new ParameterizedMessage(
                         "[{}] skipping result processing for request [{}] as the request has timed out",
-                        processContext.task.getModelId(),
+                        context.task.getModelId(),
                         requestId
                     )
                 );
                 return;
             }
             InferenceResults results = inferenceResultsProcessor.processResult(tokenization, pyTorchResult);
-            logger.debug(
-                () -> new ParameterizedMessage("[{}] processed result for request [{}]", processContext.task.getModelId(), requestId)
-            );
-            listener.onResponse(results);
+            logger.debug(() -> new ParameterizedMessage("[{}] processed result for request [{}]", context.task.getModelId(), requestId));
+            resultsListener.onResponse(results);
         }
     }
 
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/TrainedModelDeploymentTask.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/TrainedModelDeploymentTask.java
index d16c7adc7f2d..6d88e12cabc0 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/TrainedModelDeploymentTask.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/deployment/TrainedModelDeploymentTask.java
@@ -35,8 +35,8 @@ public class TrainedModelDeploymentTask extends CancellableTask implements Start
     private final TaskParams params;
     private final TrainedModelAllocationNodeService trainedModelAllocationNodeService;
     private volatile boolean stopped;
-    private final SetOnce<String> stoppedReason = new SetOnce<>();
-    private final SetOnce<InferenceConfig> inferenceConfig = new SetOnce<>();
+    private final SetOnce<String> stoppedReasonHolder = new SetOnce<>();
+    private final SetOnce<InferenceConfig> inferenceConfigHolder = new SetOnce<>();
     private final XPackLicenseState licenseState;
     private final LicensedFeature.Persistent licensedFeature;
 
@@ -62,7 +62,7 @@ public class TrainedModelDeploymentTask extends CancellableTask implements Start
     }
 
     void init(InferenceConfig inferenceConfig) {
-        this.inferenceConfig.set(inferenceConfig);
+        this.inferenceConfigHolder.set(inferenceConfig);
         licensedFeature.startTracking(licenseState, "model-" + params.getModelId());
     }
 
@@ -82,14 +82,14 @@ public class TrainedModelDeploymentTask extends CancellableTask implements Start
         logger.debug("[{}] Stopping due to reason [{}]", getModelId(), reason);
         licensedFeature.stopTracking(licenseState, "model-" + params.getModelId());
         stopped = true;
-        stoppedReason.trySet(reason);
+        stoppedReasonHolder.trySet(reason);
         trainedModelAllocationNodeService.stopDeploymentAndNotify(this, reason);
     }
 
     public void stopWithoutNotification(String reason) {
         licensedFeature.stopTracking(licenseState, "model-" + params.getModelId());
         logger.debug("[{}] Stopping due to reason [{}]", getModelId(), reason);
-        stoppedReason.trySet(reason);
+        stoppedReasonHolder.trySet(reason);
         stopped = true;
     }
 
@@ -98,7 +98,7 @@ public class TrainedModelDeploymentTask extends CancellableTask implements Start
     }
 
     public Optional<String> stoppedReason() {
-        return Optional.ofNullable(stoppedReason.get());
+        return Optional.ofNullable(stoppedReasonHolder.get());
     }
 
     @Override
@@ -108,24 +108,24 @@ public class TrainedModelDeploymentTask extends CancellableTask implements Start
     }
 
     public void infer(Map<String, Object> doc, InferenceConfigUpdate update, TimeValue timeout, ActionListener<InferenceResults> listener) {
-        if (inferenceConfig.get() == null) {
+        if (inferenceConfigHolder.get() == null) {
             listener.onFailure(
                 ExceptionsHelper.badRequestException("[{}] inference not possible against uninitialized model", params.getModelId())
             );
             return;
         }
-        if (update.isSupported(inferenceConfig.get()) == false) {
+        if (update.isSupported(inferenceConfigHolder.get()) == false) {
             listener.onFailure(
                 ExceptionsHelper.badRequestException(
                     "[{}] inference not possible. Task is configured with [{}] but received update of type [{}]",
                     params.getModelId(),
-                    inferenceConfig.get().getName(),
+                    inferenceConfigHolder.get().getName(),
                     update.getName()
                 )
             );
             return;
         }
-        trainedModelAllocationNodeService.infer(this, update.apply(inferenceConfig.get()), doc, timeout, listener);
+        trainedModelAllocationNodeService.infer(this, update.apply(inferenceConfigHolder.get()), doc, timeout, listener);
     }
 
     public Optional<ModelStats> modelStats() {
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/nlp/ZeroShotClassificationProcessor.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/nlp/ZeroShotClassificationProcessor.java
index df73e581f196..90f6f3e09c8f 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/nlp/ZeroShotClassificationProcessor.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/nlp/ZeroShotClassificationProcessor.java
@@ -68,35 +68,35 @@ public class ZeroShotClassificationProcessor implements NlpTask.Processor {
 
     @Override
     public NlpTask.RequestBuilder getRequestBuilder(NlpConfig nlpConfig) {
-        final String[] labels;
+        final String[] labelsValue;
         if (nlpConfig instanceof ZeroShotClassificationConfig) {
             ZeroShotClassificationConfig zeroShotConfig = (ZeroShotClassificationConfig) nlpConfig;
-            labels = zeroShotConfig.getLabels().toArray(new String[0]);
+            labelsValue = zeroShotConfig.getLabels().toArray(new String[0]);
         } else {
-            labels = this.labels;
+            labelsValue = this.labels;
         }
-        if (labels == null || labels.length == 0) {
+        if (labelsValue == null || labelsValue.length == 0) {
             throw ExceptionsHelper.badRequestException("zero_shot_classification requires non-empty [labels]");
         }
-        return new RequestBuilder(tokenizer, labels, hypothesisTemplate);
+        return new RequestBuilder(tokenizer, labelsValue, hypothesisTemplate);
     }
 
     @Override
     public NlpTask.ResultProcessor getResultProcessor(NlpConfig nlpConfig) {
-        final String[] labels;
-        final boolean isMultiLabel;
-        final String resultsField;
+        final String[] labelsValue;
+        final boolean isMultiLabelValue;
+        final String resultsFieldValue;
         if (nlpConfig instanceof ZeroShotClassificationConfig) {
             ZeroShotClassificationConfig zeroShotConfig = (ZeroShotClassificationConfig) nlpConfig;
-            labels = zeroShotConfig.getLabels().toArray(new String[0]);
-            isMultiLabel = zeroShotConfig.isMultiLabel();
-            resultsField = zeroShotConfig.getResultsField();
+            labelsValue = zeroShotConfig.getLabels().toArray(new String[0]);
+            isMultiLabelValue = zeroShotConfig.isMultiLabel();
+            resultsFieldValue = zeroShotConfig.getResultsField();
         } else {
-            labels = this.labels;
-            isMultiLabel = this.isMultiLabel;
-            resultsField = this.resultsField;
+            labelsValue = this.labels;
+            isMultiLabelValue = this.isMultiLabel;
+            resultsFieldValue = this.resultsField;
         }
-        return new ResultProcessor(entailmentPos, contraPos, labels, isMultiLabel, resultsField);
+        return new ResultProcessor(entailmentPos, contraPos, labelsValue, isMultiLabelValue, resultsFieldValue);
     }
 
     static class RequestBuilder implements NlpTask.RequestBuilder {
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/pytorch/process/PyTorchResultProcessor.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/pytorch/process/PyTorchResultProcessor.java
index d4222976b28d..f148e4a9b478 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/pytorch/process/PyTorchResultProcessor.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/pytorch/process/PyTorchResultProcessor.java
@@ -70,7 +70,7 @@ public class PyTorchResultProcessor {
                 logger.error(new ParameterizedMessage("[{}] Error processing results", deploymentId), e);
             }
             pendingResults.forEach(
-                (id, pendingResults) -> pendingResults.listener.onResponse(
+                (id, pendingResult) -> pendingResult.listener.onResponse(
                     new PyTorchResult(
                         id,
                         null,
@@ -84,7 +84,7 @@ public class PyTorchResultProcessor {
             pendingResults.clear();
         } finally {
             pendingResults.forEach(
-                (id, pendingResults) -> pendingResults.listener.onResponse(
+                (id, pendingResult) -> pendingResult.listener.onResponse(
                     new PyTorchResult(id, null, null, "inference canceled as process is stopping")
                 )
             );
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/JobManager.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/JobManager.java
index ef7a2e1c8f6c..78a0f543d9ed 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/JobManager.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/JobManager.java
@@ -370,7 +370,7 @@ public class JobManager {
 
     public void deleteJob(
         DeleteJobAction.Request request,
-        Client client,
+        Client clientToUse,
         ClusterState state,
         ActionListener<AcknowledgedResponse> listener
     ) {
@@ -404,7 +404,7 @@ public class JobManager {
         );
 
         // Step 1. Delete the physical storage
-        new JobDataDeleter(client, jobId).deleteJobDocuments(
+        new JobDataDeleter(clientToUse, jobId).deleteJobDocuments(
             jobConfigProvider,
             indexNameExpressionResolver,
             state,
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/UpdateJobProcessNotifier.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/UpdateJobProcessNotifier.java
index b03b8bf87c24..d824f17304e9 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/UpdateJobProcessNotifier.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/UpdateJobProcessNotifier.java
@@ -85,9 +85,9 @@ public class UpdateJobProcessNotifier {
     private void stop() {
         orderedJobUpdates.clear();
 
-        ThreadPool.Cancellable cancellable = this.cancellable;
-        if (cancellable != null) {
-            cancellable.cancel();
+        ThreadPool.Cancellable cancellableCopy = this.cancellable;
+        if (cancellableCopy != null) {
+            cancellableCopy.cancel();
         }
     }
 
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobDataDeleter.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobDataDeleter.java
index 85e4c8123493..3304bccb906c 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobDataDeleter.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobDataDeleter.java
@@ -421,7 +421,11 @@ public class JobDataDeleter {
         deleteModelState(jobId, deleteStateHandler);
     }
 
-    private void deleteResultsByQuery(String jobId, String[] indices, ActionListener<BulkByScrollResponse> listener) {
+    private void deleteResultsByQuery(
+        @SuppressWarnings("HiddenField") String jobId,
+        String[] indices,
+        ActionListener<BulkByScrollResponse> listener
+    ) {
         assert indices.length > 0;
 
         ActionListener<RefreshResponse> refreshListener = ActionListener.wrap(refreshResponse -> {
@@ -442,7 +446,7 @@ public class JobDataDeleter {
         executeAsyncWithOrigin(client, ML_ORIGIN, RefreshAction.INSTANCE, refreshRequest, refreshListener);
     }
 
-    private void deleteAliases(String jobId, ActionListener<AcknowledgedResponse> finishedHandler) {
+    private void deleteAliases(@SuppressWarnings("HiddenField") String jobId, ActionListener<AcknowledgedResponse> finishedHandler) {
         final String readAliasName = AnomalyDetectorsIndex.jobResultsAliasedName(jobId);
         final String writeAliasName = AnomalyDetectorsIndex.resultsWriteAlias(jobId);
 
@@ -494,7 +498,7 @@ public class JobDataDeleter {
             );
     }
 
-    private void deleteQuantiles(String jobId, ActionListener<Boolean> finishedHandler) {
+    private void deleteQuantiles(@SuppressWarnings("HiddenField") String jobId, ActionListener<Boolean> finishedHandler) {
         // Just use ID here, not type, as trying to delete different types spams the logs with an exception stack trace
         IdsQueryBuilder query = new IdsQueryBuilder().addIds(Quantiles.documentId(jobId));
         DeleteByQueryRequest request = new DeleteByQueryRequest(AnomalyDetectorsIndex.jobStateIndexPattern()).setQuery(query)
@@ -511,7 +515,7 @@ public class JobDataDeleter {
         );
     }
 
-    private void deleteModelState(String jobId, ActionListener<BulkByScrollResponse> listener) {
+    private void deleteModelState(@SuppressWarnings("HiddenField") String jobId, ActionListener<BulkByScrollResponse> listener) {
         GetModelSnapshotsAction.Request request = new GetModelSnapshotsAction.Request(jobId, null);
         request.setPageParams(new PageParams(0, MAX_SNAPSHOTS_TO_DELETE));
         executeAsyncWithOrigin(client, ML_ORIGIN, GetModelSnapshotsAction.INSTANCE, request, ActionListener.wrap(response -> {
@@ -520,7 +524,11 @@ public class JobDataDeleter {
         }, listener::onFailure));
     }
 
-    private void deleteCategorizerState(String jobId, int docNum, ActionListener<Boolean> finishedHandler) {
+    private void deleteCategorizerState(
+        @SuppressWarnings("HiddenField") String jobId,
+        int docNum,
+        ActionListener<Boolean> finishedHandler
+    ) {
         // Just use ID here, not type, as trying to delete different types spams the logs with an exception stack trace
         IdsQueryBuilder query = new IdsQueryBuilder().addIds(CategorizerState.documentId(jobId, docNum));
         DeleteByQueryRequest request = new DeleteByQueryRequest(AnomalyDetectorsIndex.jobStateIndexPattern()).setQuery(query)
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsPersister.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsPersister.java
index f9c9079b797e..15de78dc6811 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsPersister.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsPersister.java
@@ -132,7 +132,10 @@ public class JobResultsPersister {
             return this;
         }
 
-        private void persistBucketInfluencersStandalone(String jobId, List<BucketInfluencer> bucketInfluencers) {
+        private void persistBucketInfluencersStandalone(
+            @SuppressWarnings("HiddenField") String jobId,
+            List<BucketInfluencer> bucketInfluencers
+        ) {
             if (bucketInfluencers != null && bucketInfluencers.isEmpty() == false) {
                 for (BucketInfluencer bucketInfluencer : bucketInfluencers) {
                     String id = bucketInfluencer.getId();
@@ -508,7 +511,7 @@ public class JobResultsPersister {
         }
 
         BulkResponse persist(Supplier<Boolean> shouldRetry, boolean requireAlias) {
-            logCall(indexName);
+            logCall();
             try {
                 return resultsPersisterService.indexWithRetry(
                     jobId,
@@ -533,7 +536,7 @@ public class JobResultsPersister {
         }
 
         void persist(ActionListener<IndexResponse> listener, boolean requireAlias) {
-            logCall(indexName);
+            logCall();
 
             try (XContentBuilder content = toXContentBuilder(object, params)) {
                 IndexRequest indexRequest = new IndexRequest(indexName).id(id)
@@ -549,7 +552,7 @@ public class JobResultsPersister {
             }
         }
 
-        private void logCall(String indexName) {
+        private void logCall() {
             if (logger.isTraceEnabled()) {
                 if (id != null) {
                     logger.trace("[{}] ES API CALL: to index {} with ID [{}]", jobId, indexName, id);
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java
index 01784ad9de1d..bbf537d084e5 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java
@@ -758,7 +758,7 @@ public class JobResultsProvider {
         BucketsQueryBuilder query,
         Consumer<QueryPage<Bucket>> handler,
         Consumer<Exception> errorHandler,
-        Client client
+        @SuppressWarnings("HiddenField") Client client
     ) throws ResourceNotFoundException {
 
         String indexName = AnomalyDetectorsIndex.jobResultsAliasedName(jobId);
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/RecordsQueryBuilder.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/RecordsQueryBuilder.java
index 865660edb824..9ccaed707e7a 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/RecordsQueryBuilder.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/RecordsQueryBuilder.java
@@ -137,8 +137,8 @@ public final class RecordsQueryBuilder {
             .sort(sb)
             .fetchSource(true);
 
-        for (String sortField : SECONDARY_SORT) {
-            searchSourceBuilder.sort(sortField, sortDescending ? SortOrder.DESC : SortOrder.ASC);
+        for (String eachSortField : SECONDARY_SORT) {
+            searchSourceBuilder.sort(eachSortField, sortDescending ? SortOrder.DESC : SortOrder.ASC);
         }
 
         return searchSourceBuilder;
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/ProcessContext.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/ProcessContext.java
index 4d79873d0183..49b02bdd6ae7 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/ProcessContext.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/ProcessContext.java
@@ -69,9 +69,9 @@ final class ProcessContext {
         lock.unlock();
     }
 
-    void setRunning(AutodetectCommunicator autodetectCommunicator) {
+    void setRunning(AutodetectCommunicator communicator) {
         assert lock.isHeldByCurrentThread();
-        state.setRunning(this, autodetectCommunicator);
+        state.setRunning(this, communicator);
     }
 
     boolean setDying() {
diff --git a/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/v2/RollupActionSingleNodeTests.java b/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/v2/RollupActionSingleNodeTests.java
index d86d7e0cf204..4252bfc6b213 100644
--- a/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/v2/RollupActionSingleNodeTests.java
+++ b/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/v2/RollupActionSingleNodeTests.java
@@ -414,37 +414,41 @@ public class RollupActionSingleNodeTests extends ESSingleNodeTestCase {
     }
 
     @SuppressWarnings("unchecked")
-    private void assertRollupIndex(RollupActionConfig config, String sourceIndex, String rollupIndex) {
+    private void assertRollupIndex(RollupActionConfig config, String sourceIndex, String rollupIndexName) {
         final CompositeAggregationBuilder aggregation = buildCompositeAggs("resp", config);
         long numBuckets = 0;
         InternalComposite origResp = client().prepareSearch(sourceIndex).addAggregation(aggregation).get().getAggregations().get("resp");
-        InternalComposite rollupResp = client().prepareSearch(rollupIndex).addAggregation(aggregation).get().getAggregations().get("resp");
+        InternalComposite rollupResp = client().prepareSearch(rollupIndexName)
+            .addAggregation(aggregation)
+            .get()
+            .getAggregations()
+            .get("resp");
         while (origResp.afterKey() != null) {
             numBuckets += origResp.getBuckets().size();
             assertThat(origResp, equalTo(rollupResp));
             aggregation.aggregateAfter(origResp.afterKey());
             origResp = client().prepareSearch(sourceIndex).addAggregation(aggregation).get().getAggregations().get("resp");
-            rollupResp = client().prepareSearch(rollupIndex).addAggregation(aggregation).get().getAggregations().get("resp");
+            rollupResp = client().prepareSearch(rollupIndexName).addAggregation(aggregation).get().getAggregations().get("resp");
         }
         assertThat(origResp, equalTo(rollupResp));
 
-        SearchResponse resp = client().prepareSearch(rollupIndex).setTrackTotalHits(true).get();
+        SearchResponse resp = client().prepareSearch(rollupIndexName).setTrackTotalHits(true).get();
         assertThat(resp.getHits().getTotalHits().value, equalTo(numBuckets));
 
-        GetIndexResponse indexSettingsResp = client().admin().indices().prepareGetIndex().addIndices(sourceIndex, rollupIndex).get();
+        GetIndexResponse indexSettingsResp = client().admin().indices().prepareGetIndex().addIndices(sourceIndex, rollupIndexName).get();
         // Assert rollup metadata are set in index settings
         assertEquals(
             indexSettingsResp.getSetting(sourceIndex, "index.uuid"),
-            indexSettingsResp.getSetting(rollupIndex, "index.rollup.source.uuid")
+            indexSettingsResp.getSetting(rollupIndexName, "index.rollup.source.uuid")
         );
         assertEquals(
             indexSettingsResp.getSetting(sourceIndex, "index.provided_name"),
-            indexSettingsResp.getSetting(rollupIndex, "index.rollup.source.name")
+            indexSettingsResp.getSetting(rollupIndexName, "index.rollup.source.name")
         );
 
         // Assert field mappings
         Map<String, Map<String, Object>> mappings = (Map<String, Map<String, Object>>) indexSettingsResp.getMappings()
-            .get(rollupIndex)
+            .get(rollupIndexName)
             .getSourceAsMap()
             .get("properties");
 
@@ -485,7 +489,7 @@ public class RollupActionSingleNodeTests extends ESSingleNodeTestCase {
         // Assert that temporary index was removed
         expectThrows(
             IndexNotFoundException.class,
-            () -> client().admin().indices().prepareGetIndex().addIndices(".rolluptmp-" + rollupIndex).get()
+            () -> client().admin().indices().prepareGetIndex().addIndices(".rolluptmp-" + rollupIndexName).get()
         );
     }
 
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshots.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshots.java
index c6c353fac4b1..f226257efda4 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshots.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshots.java
@@ -399,7 +399,7 @@ public class SearchableSnapshots extends Plugin implements IndexStorePlugin, Eng
     }
 
     @Override
-    public Collection<SystemIndexDescriptor> getSystemIndexDescriptors(Settings settings) {
+    public Collection<SystemIndexDescriptor> getSystemIndexDescriptors(Settings unused) {
         return List.of(
             SystemIndexDescriptor.builder()
                 .setIndexPattern(SNAPSHOT_BLOB_CACHE_INDEX_PATTERN)
@@ -506,7 +506,7 @@ public class SearchableSnapshots extends Plugin implements IndexStorePlugin, Eng
     }
 
     public List<RestHandler> getRestHandlers(
-        Settings settings,
+        Settings unused,
         RestController restController,
         ClusterSettings clusterSettings,
         IndexScopedSettings indexScopedSettings,
@@ -533,11 +533,11 @@ public class SearchableSnapshots extends Plugin implements IndexStorePlugin, Eng
     }
 
     @Override
-    public Collection<AllocationDecider> createAllocationDeciders(Settings settings, ClusterSettings clusterSettings) {
+    public Collection<AllocationDecider> createAllocationDeciders(Settings settingsToUse, ClusterSettings clusterSettings) {
         return List.of(
             new SearchableSnapshotAllocationDecider(() -> SEARCHABLE_SNAPSHOT_FEATURE.checkWithoutTracking(getLicenseState())),
             new SearchableSnapshotRepositoryExistsAllocationDecider(),
-            new SearchableSnapshotEnableAllocationDecider(settings, clusterSettings),
+            new SearchableSnapshotEnableAllocationDecider(settingsToUse, clusterSettings),
             new HasFrozenCacheAllocationDecider(frozenCacheInfoService),
             new DedicatedFrozenNodeAllocationDecider()
         );
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/action/SearchableSnapshotsStatsResponse.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/action/SearchableSnapshotsStatsResponse.java
index 00a710421cb4..e7e9dcd75b9f 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/action/SearchableSnapshotsStatsResponse.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/action/SearchableSnapshotsStatsResponse.java
@@ -94,7 +94,7 @@ public class SearchableSnapshotsStatsResponse extends BroadcastResponse {
         if ("indices".equalsIgnoreCase(level) || "shards".equalsIgnoreCase(level)) {
             builder.startObject("indices");
             final List<Index> indices = getStats().stream()
-                .filter(stats -> stats.getStats().isEmpty() == false)
+                .filter(shardStats -> shardStats.getStats().isEmpty() == false)
                 .map(SearchableSnapshotShardStats::getShardRouting)
                 .map(ShardRouting::index)
                 .sorted(Comparator.comparing(Index::getName))
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/FailShardsOnInvalidLicenseClusterListener.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/FailShardsOnInvalidLicenseClusterListener.java
index d7ad0865b207..beb5e5c727e3 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/FailShardsOnInvalidLicenseClusterListener.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/FailShardsOnInvalidLicenseClusterListener.java
@@ -62,8 +62,8 @@ public class FailShardsOnInvalidLicenseClusterListener implements LicenseStateLi
 
     @Override
     public synchronized void licenseStateChanged() {
-        final boolean allowed = SEARCHABLE_SNAPSHOT_FEATURE.checkWithoutTracking(xPackLicenseState);
-        if (allowed && this.allowed == false) {
+        final boolean isAllowed = SEARCHABLE_SNAPSHOT_FEATURE.checkWithoutTracking(xPackLicenseState);
+        if (isAllowed && this.allowed == false) {
             rerouteService.reroute("reroute after license activation", Priority.NORMAL, new ActionListener<ClusterState>() {
                 @Override
                 public void onResponse(ClusterState clusterState) {
@@ -76,7 +76,7 @@ public class FailShardsOnInvalidLicenseClusterListener implements LicenseStateLi
                 }
             });
         }
-        this.allowed = allowed;
+        this.allowed = isAllowed;
         failActiveShardsIfNecessary();
     }
 
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/SearchableSnapshotIndexFoldersDeletionListener.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/SearchableSnapshotIndexFoldersDeletionListener.java
index bc41b2c7f0c4..3805e965c1b0 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/SearchableSnapshotIndexFoldersDeletionListener.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/SearchableSnapshotIndexFoldersDeletionListener.java
@@ -33,15 +33,15 @@ public class SearchableSnapshotIndexFoldersDeletionListener implements IndexStor
 
     private static final Logger logger = LogManager.getLogger(SearchableSnapshotIndexEventListener.class);
 
-    private final Supplier<CacheService> cacheService;
-    private final Supplier<FrozenCacheService> frozenCacheService;
+    private final Supplier<CacheService> cacheServiceSupplier;
+    private final Supplier<FrozenCacheService> frozenCacheServiceSupplier;
 
     public SearchableSnapshotIndexFoldersDeletionListener(
-        Supplier<CacheService> cacheService,
-        Supplier<FrozenCacheService> frozenCacheService
+        Supplier<CacheService> cacheServiceSupplier,
+        Supplier<FrozenCacheService> frozenCacheServiceSupplier
     ) {
-        this.cacheService = Objects.requireNonNull(cacheService);
-        this.frozenCacheService = Objects.requireNonNull(frozenCacheService);
+        this.cacheServiceSupplier = Objects.requireNonNull(cacheServiceSupplier);
+        this.frozenCacheServiceSupplier = Objects.requireNonNull(frozenCacheServiceSupplier);
     }
 
     @Override
@@ -61,7 +61,7 @@ public class SearchableSnapshotIndexFoldersDeletionListener implements IndexStor
     }
 
     private void markShardAsEvictedInCache(ShardId shardId, IndexSettings indexSettings) {
-        final CacheService cacheService = this.cacheService.get();
+        final CacheService cacheService = this.cacheServiceSupplier.get();
         assert cacheService != null : "cache service not initialized";
 
         logger.debug("{} marking shard as evicted in searchable snapshots cache (reason: cache files deleted from disk)", shardId);
@@ -71,7 +71,7 @@ public class SearchableSnapshotIndexFoldersDeletionListener implements IndexStor
             shardId
         );
 
-        final FrozenCacheService frozenCacheService = this.frozenCacheService.get();
+        final FrozenCacheService frozenCacheService = this.frozenCacheServiceSupplier.get();
         assert frozenCacheService != null : "frozen cache service not initialized";
         frozenCacheService.markShardAsEvictedInCache(
             SNAPSHOT_SNAPSHOT_ID_SETTING.get(indexSettings.getSettings()),
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/decider/SearchableSnapshotEnableAllocationDecider.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/decider/SearchableSnapshotEnableAllocationDecider.java
index 938feb030340..c2a02acb3b8b 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/decider/SearchableSnapshotEnableAllocationDecider.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/decider/SearchableSnapshotEnableAllocationDecider.java
@@ -65,16 +65,16 @@ public class SearchableSnapshotEnableAllocationDecider extends AllocationDecider
     public Decision canAllocate(ShardRouting shardRouting, RoutingAllocation allocation) {
         final IndexMetadata indexMetadata = allocation.metadata().getIndexSafe(shardRouting.index());
         if (SearchableSnapshotsSettings.isSearchableSnapshotStore(indexMetadata.getSettings())) {
-            EnableAllocationDecider.Allocation enableAllocation = this.enableAllocation;
-            boolean allocateOnRollingRestart = this.allocateOnRollingRestart;
-            if (enableAllocation == EnableAllocationDecider.Allocation.PRIMARIES) {
-                if (allocateOnRollingRestart == false) {
+            EnableAllocationDecider.Allocation enableAllocationCopy = this.enableAllocation;
+            boolean allocateOnRollingRestartCopy = this.allocateOnRollingRestart;
+            if (enableAllocationCopy == EnableAllocationDecider.Allocation.PRIMARIES) {
+                if (allocateOnRollingRestartCopy == false) {
                     return allocation.decision(
                         Decision.NO,
                         NAME,
                         "no allocations of searchable snapshots allowed during rolling restart due to [%s=%s] and [%s=false]",
                         EnableAllocationDecider.CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING.getKey(),
-                        enableAllocation,
+                        enableAllocationCopy,
                         SEARCHABLE_SNAPSHOTS_ALLOCATE_ON_ROLLING_RESTART.getKey()
                     );
                 } else {
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/blob/BlobStoreCacheMaintenanceService.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/blob/BlobStoreCacheMaintenanceService.java
index d24265dfd597..af3bac6963ff 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/blob/BlobStoreCacheMaintenanceService.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/blob/BlobStoreCacheMaintenanceService.java
@@ -523,8 +523,8 @@ public class BlobStoreCacheMaintenanceService implements ClusterStateListener {
                     assert knownSnapshots != null;
                     final Set<String> knownRepositories = existingRepositories;
                     assert knownRepositories != null;
-                    final Instant expirationTime = this.expirationTime;
-                    assert expirationTime != null;
+                    final Instant expirationTimeCopy = this.expirationTime;
+                    assert expirationTimeCopy != null;
 
                     Object[] lastSortValues = null;
                     for (SearchHit searchHit : searchHits) {
@@ -551,7 +551,7 @@ public class BlobStoreCacheMaintenanceService implements ClusterStateListener {
                             }
                             if (delete) {
                                 final Instant creationTime = getCreationTime(searchHit);
-                                if (creationTime.isAfter(expirationTime)) {
+                                if (creationTime.isAfter(expirationTimeCopy)) {
                                     logger.trace(
                                         "blob store cache entry with id [{}] was created recently, skipping deletion",
                                         searchHit.getId()
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ByteRange.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ByteRange.java
index e6196874bfe3..8ba31d1304cd 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ByteRange.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ByteRange.java
@@ -65,8 +65,8 @@ public final class ByteRange implements Comparable<ByteRange> {
         return start >= range.start() && end <= range.end();
     }
 
-    public boolean contains(long start, long end) {
-        return start() <= start && end <= end();
+    public boolean contains(long rangeStart, long rangeEnd) {
+        return start() <= rangeStart && rangeEnd <= end();
     }
 
     public ByteRange shift(long delta) {
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/CacheFile.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/CacheFile.java
index a827b8f3d610..cdffe597fd81 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/CacheFile.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/CacheFile.java
@@ -180,8 +180,8 @@ public class CacheFile {
         return tracker.getInitialLength();
     }
 
-    public void acquire(final EvictionListener listener) throws IOException {
-        assert listener != null;
+    public void acquire(final EvictionListener evictionListener) throws IOException {
+        assert evictionListener != null;
 
         ensureOpen();
         boolean success = false;
@@ -194,8 +194,8 @@ public class CacheFile {
                         channelRef = new FileChannelReference(fileExists ? OPEN_OPTIONS : CREATE_OPTIONS);
                         fileExists = true;
                     }
-                    final boolean added = listeners.add(listener);
-                    assert added : "listener already exists " + listener;
+                    final boolean added = listeners.add(evictionListener);
+                    assert added : "listener already exists " + evictionListener;
                 }
                 success = true;
             } finally {
@@ -210,14 +210,14 @@ public class CacheFile {
         assert invariant();
     }
 
-    public void release(final EvictionListener listener) {
-        assert listener != null;
+    public void release(final EvictionListener evictionListener) {
+        assert evictionListener != null;
 
         boolean success = false;
         try {
             synchronized (listeners) {
-                final boolean removed = listeners.remove(Objects.requireNonNull(listener));
-                assert removed : "listener does not exist " + listener;
+                final boolean removed = listeners.remove(Objects.requireNonNull(evictionListener));
+                assert removed : "listener does not exist " + evictionListener;
                 if (removed == false) {
                     throw new IllegalStateException("Cannot remove an unknown listener");
                 }
@@ -251,15 +251,15 @@ public class CacheFile {
 
     private boolean assertRefCounted(boolean isReleased) {
         final boolean isEvicted = evicted.get();
-        final boolean fileExists = Files.exists(file);
-        assert isReleased == false || (isEvicted && fileExists == false)
+        final boolean fileDoesExist = Files.exists(file);
+        assert isReleased == false || (isEvicted && fileDoesExist == false)
             : "fully released cache file should be deleted from disk but got ["
                 + "released="
                 + isReleased
                 + ", evicted="
                 + isEvicted
                 + ", file exists="
-                + fileExists
+                + fileDoesExist
                 + ']';
         return true;
     }
@@ -274,7 +274,7 @@ public class CacheFile {
                 evictionListeners = new HashSet<>(listeners);
             }
             decrementRefCount();
-            evictionListeners.forEach(listener -> listener.onEviction(this));
+            evictionListeners.forEach(eachListener -> eachListener.onEviction(this));
         }
         assert invariant();
     }
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ProgressListenableActionFuture.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ProgressListenableActionFuture.java
index 225b72192c00..a0ae32404d86 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ProgressListenableActionFuture.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/common/ProgressListenableActionFuture.java
@@ -65,30 +65,30 @@ class ProgressListenableActionFuture extends AdapterActionFuture<Long, Long> {
      * (inclusive) to {@code progress} (exclusive) is available. Calling this method potentially triggers the execution of one or
      * more listeners that are waiting for the progress to reach a value lower than the one just updated.
      *
-     * @param progress the new progress value
+     * @param progressValue the new progress value
      */
-    public void onProgress(final long progress) {
+    public void onProgress(final long progressValue) {
         ensureNotCompleted();
 
-        if (progress <= start) {
-            assert false : progress + " <= " + start;
+        if (progressValue <= start) {
+            assert false : progressValue + " <= " + start;
             throw new IllegalArgumentException("Cannot update progress with a value less than [start=" + start + ']');
         }
-        if (end < progress) {
-            assert false : end + " < " + progress;
+        if (end < progressValue) {
+            assert false : end + " < " + progressValue;
             throw new IllegalArgumentException("Cannot update progress with a value greater than [end=" + end + ']');
         }
 
         List<ActionListener<Long>> listenersToExecute = null;
         synchronized (this) {
-            assert this.progress < progress : this.progress + " < " + progress;
-            this.progress = progress;
+            assert this.progress < progressValue : this.progress + " < " + progressValue;
+            this.progress = progressValue;
 
-            final List<Tuple<Long, ActionListener<Long>>> listeners = this.listeners;
-            if (listeners != null) {
+            final List<Tuple<Long, ActionListener<Long>>> listenersCopy = this.listeners;
+            if (listenersCopy != null) {
                 List<Tuple<Long, ActionListener<Long>>> listenersToKeep = null;
-                for (Tuple<Long, ActionListener<Long>> listener : listeners) {
-                    if (progress < listener.v1()) {
+                for (Tuple<Long, ActionListener<Long>> listener : listenersCopy) {
+                    if (progressValue < listener.v1()) {
                         if (listenersToKeep == null) {
                             listenersToKeep = new ArrayList<>();
                         }
@@ -104,7 +104,7 @@ class ProgressListenableActionFuture extends AdapterActionFuture<Long, Long> {
             }
         }
         if (listenersToExecute != null) {
-            listenersToExecute.forEach(listener -> executeListener(listener, () -> progress));
+            listenersToExecute.forEach(listener -> executeListener(listener, () -> progressValue));
         }
         assert invariant();
     }
@@ -152,22 +152,22 @@ class ProgressListenableActionFuture extends AdapterActionFuture<Long, Long> {
      */
     public void addListener(ActionListener<Long> listener, long value) {
         boolean executeImmediate = false;
-        final long progress;
+        final long progressValue;
         synchronized (this) {
-            progress = this.progress;
-            if (completed || value <= progress) {
+            progressValue = this.progress;
+            if (completed || value <= progressValue) {
                 executeImmediate = true;
             } else {
-                List<Tuple<Long, ActionListener<Long>>> listeners = this.listeners;
-                if (listeners == null) {
-                    listeners = new ArrayList<>();
+                List<Tuple<Long, ActionListener<Long>>> listenersCopy = this.listeners;
+                if (listenersCopy == null) {
+                    listenersCopy = new ArrayList<>();
                 }
-                listeners.add(Tuple.tuple(value, listener));
-                this.listeners = listeners;
+                listenersCopy.add(Tuple.tuple(value, listener));
+                this.listeners = listenersCopy;
             }
         }
         if (executeImmediate) {
-            executeListener(listener, completed ? () -> actionGet(0L) : () -> progress);
+            executeListener(listener, completed ? () -> actionGet(0L) : () -> progressValue);
         }
         assert invariant();
     }
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/shared/FrozenCacheService.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/shared/FrozenCacheService.java
index 7097767efe47..56a81287390f 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/shared/FrozenCacheService.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/cache/shared/FrozenCacheService.java
@@ -372,13 +372,13 @@ public class FrozenCacheService implements Releasable {
     }
 
     public CacheFileRegion get(CacheKey cacheKey, long fileLength, int region) {
-        final long regionSize = getRegionSize(fileLength, region);
+        final long effectiveRegionSize = getRegionSize(fileLength, region);
         try (Releasable ignore = keyedLock.acquire(cacheKey)) {
             final RegionKey regionKey = new RegionKey(cacheKey, region);
             final long now = currentTimeSupplier.getAsLong();
             final Entry<CacheFileRegion> entry = keyMapping.computeIfAbsent(
                 regionKey,
-                key -> new Entry<>(new CacheFileRegion(regionKey, regionSize), now)
+                key -> new Entry<>(new CacheFileRegion(regionKey, effectiveRegionSize), now)
             );
             if (entry.chunk.sharedBytesPos == -1) {
                 // new item
@@ -885,15 +885,15 @@ public class FrozenCacheService implements Releasable {
                 final StepListener<Integer> lis = fileRegion.populateAndRead(
                     subRangeToWrite,
                     subRangeToRead,
-                    (channel, channelPos, relativePos, length) -> {
+                    (channel, channelPos, relativePos, len) -> {
                         assert regionOwners[fileRegion.sharedBytesPos].get() == fileRegion;
-                        assert channelPos >= fileRegion.physicalStartOffset() && channelPos + length <= fileRegion.physicalEndOffset();
-                        return reader.onRangeAvailable(channel, channelPos, relativePos - readOffset, length);
+                        assert channelPos >= fileRegion.physicalStartOffset() && channelPos + len <= fileRegion.physicalEndOffset();
+                        return reader.onRangeAvailable(channel, channelPos, relativePos - readOffset, len);
                     },
-                    (channel, channelPos, relativePos, length, progressUpdater) -> {
+                    (channel, channelPos, relativePos, len, progressUpdater) -> {
                         assert regionOwners[fileRegion.sharedBytesPos].get() == fileRegion;
-                        assert channelPos >= fileRegion.physicalStartOffset() && channelPos + length <= fileRegion.physicalEndOffset();
-                        writer.fillCacheRange(channel, channelPos, relativePos - writeOffset, length, progressUpdater);
+                        assert channelPos >= fileRegion.physicalStartOffset() && channelPos + len <= fileRegion.physicalEndOffset();
+                        writer.fillCacheRange(channel, channelPos, relativePos - writeOffset, len, progressUpdater);
                     },
                     executor
                 );
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/SearchableSnapshotDirectory.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/SearchableSnapshotDirectory.java
index 5b1a82652f90..e222d4b35e8f 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/SearchableSnapshotDirectory.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/SearchableSnapshotDirectory.java
@@ -203,18 +203,19 @@ public class SearchableSnapshotDirectory extends BaseDirectory {
     }
 
     /**
-     * Loads the snapshot if and only if it the snapshot is not loaded yet.
+     * Loads the snapshot if and only if the snapshot is not loaded yet.
      *
      * @return true if the snapshot was loaded by executing this method, false otherwise
      */
-    public boolean loadSnapshot(RecoveryState recoveryState, ActionListener<Void> preWarmListener) {
-        assert recoveryState != null;
-        assert recoveryState instanceof SearchableSnapshotRecoveryState;
-        assert recoveryState.getRecoverySource().getType() == RecoverySource.Type.SNAPSHOT
-            || recoveryState.getRecoverySource().getType() == RecoverySource.Type.PEER : recoveryState.getRecoverySource().getType();
+    public boolean loadSnapshot(RecoveryState snapshotRecoveryState, ActionListener<Void> preWarmListener) {
+        assert snapshotRecoveryState != null;
+        assert snapshotRecoveryState instanceof SearchableSnapshotRecoveryState;
+        assert snapshotRecoveryState.getRecoverySource().getType() == RecoverySource.Type.SNAPSHOT
+            || snapshotRecoveryState.getRecoverySource().getType() == RecoverySource.Type.PEER
+            : snapshotRecoveryState.getRecoverySource().getType();
         assert assertCurrentThreadMayLoadSnapshot();
         // noinspection ConstantConditions in case assertions are disabled
-        if (recoveryState instanceof SearchableSnapshotRecoveryState == false) {
+        if (snapshotRecoveryState instanceof SearchableSnapshotRecoveryState == false) {
             throw new IllegalArgumentException("A SearchableSnapshotRecoveryState instance was expected");
         }
         boolean alreadyLoaded = this.loaded;
@@ -227,7 +228,7 @@ public class SearchableSnapshotDirectory extends BaseDirectory {
                     this.loaded = true;
                     cleanExistingRegularShardFiles();
                     waitForPendingEvictions();
-                    this.recoveryState = (SearchableSnapshotRecoveryState) recoveryState;
+                    this.recoveryState = (SearchableSnapshotRecoveryState) snapshotRecoveryState;
                     prewarmCache(preWarmListener);
                 }
             }
diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/input/BaseSearchableSnapshotIndexInput.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/input/BaseSearchableSnapshotIndexInput.java
index c7916e47b64a..1bf7001cb846 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/input/BaseSearchableSnapshotIndexInput.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/store/input/BaseSearchableSnapshotIndexInput.java
@@ -155,8 +155,8 @@ public abstract class BaseSearchableSnapshotIndexInput extends BufferedIndexInpu
         return success;
     }
 
-    protected ByteRange rangeToReadFromBlobCache(long position, int length) {
-        final long end = position + length;
+    protected ByteRange rangeToReadFromBlobCache(long position, int readLength) {
+        final long end = position + readLength;
         if (headerBlobCacheByteRange.contains(position, end)) {
             return headerBlobCacheByteRange;
         } else if (footerBlobCacheByteRange.contains(position, end)) {
@@ -170,23 +170,23 @@ public abstract class BaseSearchableSnapshotIndexInput extends BufferedIndexInpu
      * spans multiple blobs then this stream will request them in turn.
      *
      * @param position The start of the range of bytes to read, relative to the start of the corresponding Lucene file.
-     * @param length The number of bytes to read
+     * @param readLength The number of bytes to read
      */
-    protected InputStream openInputStreamFromBlobStore(final long position, final long length) throws IOException {
+    protected InputStream openInputStreamFromBlobStore(final long position, final long readLength) throws IOException {
         assert assertCurrentThreadMayAccessBlobStore();
         if (fileInfo.numberOfParts() == 1L) {
-            assert position + length <= fileInfo.partBytes(0)
-                : "cannot read [" + position + "-" + (position + length) + "] from [" + fileInfo + "]";
-            stats.addBlobStoreBytesRequested(length);
-            return blobContainer.readBlob(fileInfo.partName(0), position, length);
+            assert position + readLength <= fileInfo.partBytes(0)
+                : "cannot read [" + position + "-" + (position + readLength) + "] from [" + fileInfo + "]";
+            stats.addBlobStoreBytesRequested(readLength);
+            return blobContainer.readBlob(fileInfo.partName(0), position, readLength);
         } else {
             final int startPart = getPartNumberForPosition(position);
-            final int endPart = getPartNumberForPosition(position + length - 1);
+            final int endPart = getPartNumberForPosition(position + readLength - 1);
 
             for (int currentPart = startPart; currentPart <= endPart; currentPart++) {
                 final long startInPart = (currentPart == startPart) ? getRelativePositionInPart(position) : 0L;
                 final long endInPart = (currentPart == endPart)
-                    ? getRelativePositionInPart(position + length - 1) + 1
+                    ? getRelativePositionInPart(position + readLength - 1) + 1
                     : getLengthOfPart(currentPart);
                 stats.addBlobStoreBytesRequested(endInPart - startInPart);
             }
@@ -197,7 +197,7 @@ public abstract class BaseSearchableSnapshotIndexInput extends BufferedIndexInpu
                     final int currentPart = startPart + slice;
                     final long startInPart = (currentPart == startPart) ? getRelativePositionInPart(position) : 0L;
                     final long endInPart = (currentPart == endPart)
-                        ? getRelativePositionInPart(position + length - 1) + 1
+                        ? getRelativePositionInPart(position + readLength - 1) + 1
                         : getLengthOfPart(currentPart);
                     return blobContainer.readBlob(fileInfo.partName(currentPart), startInPart, endInPart - startInPart);
                 }
diff --git a/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/IndexPrivilegeIntegTests.java b/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/IndexPrivilegeIntegTests.java
index 539a60236779..3364627c2c35 100644
--- a/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/IndexPrivilegeIntegTests.java
+++ b/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/IndexPrivilegeIntegTests.java
@@ -25,7 +25,7 @@ import static org.hamcrest.Matchers.is;
 
 public class IndexPrivilegeIntegTests extends AbstractPrivilegeTestCase {
 
-    private String jsonDoc = "{ \"name\" : \"elasticsearch\", \"body\": \"foo bar\" }";
+    private final String jsonDoc = "{ \"name\" : \"elasticsearch\", \"body\": \"foo bar\" }";
 
     private static final String ROLES = "all_cluster_role:\n"
         + "  cluster: [ all ]\n"
@@ -739,9 +739,9 @@ public class IndexPrivilegeIntegTests extends AbstractPrivilegeTestCase {
                 break;
 
             case "delete":
-                String jsonDoc = "{ \"name\" : \"docToDelete\"}";
-                assertAccessIsAllowed("admin", "PUT", "/" + index + "/_doc/docToDelete", jsonDoc);
-                assertAccessIsAllowed("admin", "PUT", "/" + index + "/_doc/docToDelete2", jsonDoc);
+                String jsonDocToDelete = "{ \"name\" : \"docToDelete\"}";
+                assertAccessIsAllowed("admin", "PUT", "/" + index + "/_doc/docToDelete", jsonDocToDelete);
+                assertAccessIsAllowed("admin", "PUT", "/" + index + "/_doc/docToDelete2", jsonDocToDelete);
                 if (userIsAllowed) {
                     assertAccessIsAllowed(user, "DELETE", "/" + index + "/_doc/docToDelete");
                 } else {
diff --git a/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/SecurityClearScrollTests.java b/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/SecurityClearScrollTests.java
index 7fcc6288b456..aa6ddc969f23 100644
--- a/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/SecurityClearScrollTests.java
+++ b/x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/integration/SecurityClearScrollTests.java
@@ -96,7 +96,7 @@ public class SecurityClearScrollTests extends SecurityIntegTestCase {
         ClearScrollResponse clearScrollResponse = client().filterWithHeader(headers).prepareClearScroll().addScrollId("_all").get();
         assertThat(clearScrollResponse.isSucceeded(), is(true));
 
-        assertThatScrollIdsDoNotExist(scrollIds);
+        assertThatScrollIdsDoNotExist();
     }
 
     public void testThatClearingAllScrollIdsRequirePermissions() throws Exception {
@@ -116,10 +116,10 @@ public class SecurityClearScrollTests extends SecurityIntegTestCase {
         assertThat(clearByIdScrollResponse.isSucceeded(), is(true));
 
         // test with each id, that they do not exist
-        assertThatScrollIdsDoNotExist(scrollIds);
+        assertThatScrollIdsDoNotExist();
     }
 
-    private void assertThatScrollIdsDoNotExist(List<String> scrollIds) {
+    private void assertThatScrollIdsDoNotExist() {
         for (String scrollId : scrollIds) {
             SearchPhaseExecutionException expectedException = expectThrows(
                 SearchPhaseExecutionException.class,
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/common/CartesianPoint.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/common/CartesianPoint.java
index eed96ba9fff1..af1493f816a7 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/common/CartesianPoint.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/common/CartesianPoint.java
@@ -60,6 +60,7 @@ public class CartesianPoint implements ToXContentFragment {
         }
     }
 
+    @SuppressWarnings("HiddenField")
     public CartesianPoint resetFromCoordinates(String value, final boolean ignoreZValue) {
         String[] vals = value.split(",");
         if (vals.length > 3 || vals.length < 2) {
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/CentroidCalculator.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/CentroidCalculator.java
index 03c3eba8af0f..c00cfdba4d3c 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/CentroidCalculator.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/CentroidCalculator.java
@@ -276,21 +276,22 @@ public class CentroidCalculator {
          *  @param x the x-coordinate of the point
          * @param y the y-coordinate of the point
          * @param weight the associated weight of the coordinate
+         * @param shapeType the associated shape type of the coordinate
          */
-        private void addCoordinate(double x, double y, double weight, DimensionalShapeType dimensionalShapeType) {
+        private void addCoordinate(double x, double y, double weight, DimensionalShapeType shapeType) {
             // x and y can be infinite due to really small areas and rounding problems
             if (Double.isFinite(x) && Double.isFinite(y)) {
-                if (this.dimensionalShapeType == dimensionalShapeType) {
+                if (this.dimensionalShapeType == shapeType) {
                     compSumX.add(x * weight);
                     compSumY.add(y * weight);
                     compSumWeight.add(weight);
-                    this.dimensionalShapeType = dimensionalShapeType;
-                } else if (dimensionalShapeType.compareTo(this.dimensionalShapeType) > 0) {
+                    this.dimensionalShapeType = shapeType;
+                } else if (shapeType.compareTo(this.dimensionalShapeType) > 0) {
                     // reset counters
                     compSumX.reset(x * weight, 0);
                     compSumY.reset(y * weight, 0);
                     compSumWeight.reset(weight, 0);
-                    this.dimensionalShapeType = dimensionalShapeType;
+                    this.dimensionalShapeType = shapeType;
                 }
             }
         }
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Extent.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Extent.java
index 3e530b132d38..c132659fce94 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Extent.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Extent.java
@@ -49,6 +49,7 @@ class Extent {
         this.posRight = posRight;
     }
 
+    @SuppressWarnings("HiddenField")
     public void reset(int top, int bottom, int negLeft, int negRight, int posLeft, int posRight) {
         this.top = top;
         this.bottom = bottom;
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/GeometryDocValueReader.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/GeometryDocValueReader.java
index 04c9216e484c..0b95d5ac2666 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/GeometryDocValueReader.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/GeometryDocValueReader.java
@@ -99,11 +99,11 @@ public class GeometryDocValueReader {
      * Visit the triangle tree with the provided visitor
      */
     public void visit(TriangleTreeReader.Visitor visitor) throws IOException {
-        Extent extent = getExtent();
-        int thisMaxX = extent.maxX();
-        int thisMinX = extent.minX();
-        int thisMaxY = extent.maxY();
-        int thisMinY = extent.minY();
+        Extent geometryExtent = getExtent();
+        int thisMaxX = geometryExtent.maxX();
+        int thisMinX = geometryExtent.minX();
+        int thisMaxY = geometryExtent.maxY();
+        int thisMinY = geometryExtent.minY();
         if (visitor.push(thisMinX, thisMinY, thisMaxX, thisMaxY)) {
             TriangleTreeReader.visit(input, visitor, thisMaxX, thisMaxY);
         }
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Tile2DVisitor.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Tile2DVisitor.java
index 8150e711cd9d..7e9159234122 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Tile2DVisitor.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/fielddata/Tile2DVisitor.java
@@ -62,9 +62,9 @@ class Tile2DVisitor implements TriangleTreeReader.Visitor {
         boolean ab = (metadata & 1 << 4) == 1 << 4;
         boolean bc = (metadata & 1 << 5) == 1 << 5;
         boolean ca = (metadata & 1 << 6) == 1 << 6;
-        GeoRelation relation = relateTriangle(aX, aY, ab, bX, bY, bc, cX, cY, ca);
-        if (relation != GeoRelation.QUERY_DISJOINT) {
-            this.relation = relation;
+        GeoRelation geoRelation = relateTriangle(aX, aY, ab, bX, bY, bc, cX, cY, ca);
+        if (geoRelation != GeoRelation.QUERY_DISJOINT) {
+            this.relation = geoRelation;
         }
     }
 
@@ -89,6 +89,7 @@ class Tile2DVisitor implements TriangleTreeReader.Visitor {
     }
 
     @Override
+    @SuppressWarnings("HiddenField")
     public boolean push(int minX, int minY, int maxX, int maxY) {
         // exclude north and east boundary intersections with tiles from intersection consideration
         // for consistent tiling definition of shapes on the boundaries of tiles
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/mapper/LatLonShapeDocValuesQuery.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/mapper/LatLonShapeDocValuesQuery.java
index 1a615281ba9a..893f90f13a17 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/mapper/LatLonShapeDocValuesQuery.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/index/mapper/LatLonShapeDocValuesQuery.java
@@ -49,9 +49,9 @@ class LatLonShapeDocValuesQuery extends Query {
     }
 
     @Override
-    public String toString(String field) {
+    public String toString(String otherField) {
         StringBuilder sb = new StringBuilder();
-        if (this.field.equals(field) == false) {
+        if (this.field.equals(otherField) == false) {
             sb.append(this.field);
             sb.append(':');
             sb.append(relation);
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/InternalGeoLine.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/InternalGeoLine.java
index 0cdc49c8ba84..f2c8722dd73a 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/InternalGeoLine.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/InternalGeoLine.java
@@ -94,17 +94,17 @@ public class InternalGeoLine extends InternalAggregation implements GeoShapeMetr
     @Override
     public InternalAggregation reduce(List<InternalAggregation> aggregations, ReduceContext reduceContext) {
         int mergedSize = 0;
-        boolean complete = true;
-        boolean includeSorts = true;
+        boolean reducedComplete = true;
+        boolean reducedIncludeSorts = true;
         List<InternalGeoLine> internalGeoLines = new ArrayList<>(aggregations.size());
         for (InternalAggregation aggregation : aggregations) {
             InternalGeoLine geoLine = (InternalGeoLine) aggregation;
             internalGeoLines.add(geoLine);
             mergedSize += geoLine.line.length;
-            complete &= geoLine.complete;
-            includeSorts &= geoLine.includeSorts;
+            reducedComplete &= geoLine.complete;
+            reducedIncludeSorts &= geoLine.includeSorts;
         }
-        complete &= mergedSize <= size;
+        reducedComplete &= mergedSize <= size;
         int finalSize = Math.min(mergedSize, size);
 
         MergedGeoLines mergedGeoLines = new MergedGeoLines(internalGeoLines, finalSize, sortOrder);
@@ -118,8 +118,8 @@ public class InternalGeoLine extends InternalAggregation implements GeoShapeMetr
             mergedGeoLines.getFinalPoints(),
             mergedGeoLines.getFinalSortValues(),
             getMetadata(),
-            complete,
-            includeSorts,
+            reducedComplete,
+            reducedIncludeSorts,
             sortOrder,
             size
         );
diff --git a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/bucket/geogrid/BoundedGeoTileGridTiler.java b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/bucket/geogrid/BoundedGeoTileGridTiler.java
index ad085b1512e3..ef649a82abb9 100644
--- a/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/bucket/geogrid/BoundedGeoTileGridTiler.java
+++ b/x-pack/plugin/spatial/src/main/java/org/elasticsearch/xpack/spatial/search/aggregations/bucket/geogrid/BoundedGeoTileGridTiler.java
@@ -72,6 +72,7 @@ public class BoundedGeoTileGridTiler extends AbstractGeoTileGridTiler {
     }
 
     @Override
+    @SuppressWarnings("HiddenField")
     protected int setValuesForFullyContainedTile(int xTile, int yTile, int zTile, GeoShapeCellValues values, int valuesIndex) {
         // For every level we go down, we half each dimension. The total number of splits is equal to 1 << (levelEnd - levelStart)
         final int splits = 1 << precision - zTile;
@@ -101,9 +102,9 @@ public class BoundedGeoTileGridTiler extends AbstractGeoTileGridTiler {
                 }
             }
         } else {
-            final int minX = Math.max(this.minX, xTile * splits);
-            final int maxX = Math.min(this.maxX, xTile * splits + splits);
-            for (int i = minX; i < maxX; i++) {
+            final int _minX = Math.max(this.minX, xTile * splits);
+            final int _maxX = Math.min(this.maxX, xTile * splits + splits);
+            for (int i = _minX; i < _maxX; i++) {
                 for (int j = minY; j < maxY; j++) {
                     assert validTile(i, j, precision);
                     values.add(valuesIndex++, GeoTileUtils.longEncodeTiles(precision, i, j));
diff --git a/x-pack/plugin/text-structure/src/main/java/org/elasticsearch/xpack/textstructure/structurefinder/DelimitedTextStructureFinderFactory.java b/x-pack/plugin/text-structure/src/main/java/org/elasticsearch/xpack/textstructure/structurefinder/DelimitedTextStructureFinderFactory.java
index 1eafa2b67c20..47342d745af1 100644
--- a/x-pack/plugin/text-structure/src/main/java/org/elasticsearch/xpack/textstructure/structurefinder/DelimitedTextStructureFinderFactory.java
+++ b/x-pack/plugin/text-structure/src/main/java/org/elasticsearch/xpack/textstructure/structurefinder/DelimitedTextStructureFinderFactory.java
@@ -27,13 +27,13 @@ public class DelimitedTextStructureFinderFactory implements TextStructureFinderF
         this.trimFields = trimFields;
     }
 
-    DelimitedTextStructureFinderFactory makeSimilar(Character quote, Boolean trimFields) {
+    DelimitedTextStructureFinderFactory makeSimilar(Character quote, Boolean shouldTrimFields) {
 
         return new DelimitedTextStructureFinderFactory(
             (char) csvPreference.getDelimiterChar(),
             (quote == null) ? csvPreference.getQuoteChar() : quote,
             minFieldsPerRow,
-            (trimFields == null) ? this.trimFields : trimFields
+            (shouldTrimFields == null) ? this.trimFields : shouldTrimFields
         );
     }
 
diff --git a/x-pack/plugin/transform/src/internalClusterTest/java/org/elasticsearch/xpack/transform/checkpoint/TransformCheckpointServiceNodeTests.java b/x-pack/plugin/transform/src/internalClusterTest/java/org/elasticsearch/xpack/transform/checkpoint/TransformCheckpointServiceNodeTests.java
index e7587d2e3e3b..7c4746989c88 100644
--- a/x-pack/plugin/transform/src/internalClusterTest/java/org/elasticsearch/xpack/transform/checkpoint/TransformCheckpointServiceNodeTests.java
+++ b/x-pack/plugin/transform/src/internalClusterTest/java/org/elasticsearch/xpack/transform/checkpoint/TransformCheckpointServiceNodeTests.java
@@ -95,12 +95,12 @@ public class TransformCheckpointServiceNodeTests extends TransformSingleNodeTest
         void setShardStats(ShardStats[] shardStats) {
             this.shardStats = shardStats;
 
-            Set<String> indices = new HashSet<>();
+            Set<String> indicesSet = new HashSet<>();
             for (ShardStats s : shardStats) {
-                indices.add(s.getShardRouting().getIndexName());
+                indicesSet.add(s.getShardRouting().getIndexName());
             }
 
-            this.indices = indices.toArray(new String[0]);
+            this.indices = indicesSet.toArray(new String[0]);
         }
 
         @SuppressWarnings("unchecked")
diff --git a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/Transform.java b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/Transform.java
index 22deda76cff4..8a815340aca6 100644
--- a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/Transform.java
+++ b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/Transform.java
@@ -154,7 +154,7 @@ public class Transform extends Plugin implements SystemIndexPlugin, PersistentTa
 
     @Override
     public List<RestHandler> getRestHandlers(
-        final Settings settings,
+        final Settings unused,
         final RestController restController,
         final ClusterSettings clusterSettings,
         final IndexScopedSettings indexScopedSettings,
@@ -202,9 +202,9 @@ public class Transform extends Plugin implements SystemIndexPlugin, PersistentTa
     }
 
     @Override
-    public List<ExecutorBuilder<?>> getExecutorBuilders(Settings settings) {
+    public List<ExecutorBuilder<?>> getExecutorBuilders(Settings settingsToUse) {
         FixedExecutorBuilder indexing = new FixedExecutorBuilder(
-            settings,
+            settingsToUse,
             TASK_THREAD_POOL_NAME,
             4,
             4,
diff --git a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/ClientTransformIndexer.java b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/ClientTransformIndexer.java
index 9923e56927aa..f883d5638f72 100644
--- a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/ClientTransformIndexer.java
+++ b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/ClientTransformIndexer.java
@@ -72,7 +72,7 @@ class ClientTransformIndexer extends TransformIndexer {
     private final Client client;
     private final AtomicBoolean oldStatsCleanedUp = new AtomicBoolean(false);
 
-    private final AtomicReference<SeqNoPrimaryTermAndIndex> seqNoPrimaryTermAndIndex;
+    private final AtomicReference<SeqNoPrimaryTermAndIndex> seqNoPrimaryTermAndIndexHolder;
     private final ConcurrentHashMap<String, PointInTimeBuilder> namedPits = new ConcurrentHashMap<>();
     private volatile long pitCheckpoint;
     private volatile boolean disablePit = false;
@@ -107,7 +107,7 @@ class ClientTransformIndexer extends TransformIndexer {
             context
         );
         this.client = ExceptionsHelper.requireNonNull(client, "client");
-        this.seqNoPrimaryTermAndIndex = new AtomicReference<>(seqNoPrimaryTermAndIndex);
+        this.seqNoPrimaryTermAndIndexHolder = new AtomicReference<>(seqNoPrimaryTermAndIndex);
 
         // TODO: move into context constructor
         context.setShouldStopAtCheckpoint(shouldStopAtCheckpoint);
@@ -329,7 +329,7 @@ class ClientTransformIndexer extends TransformIndexer {
                 newValue
             )
         );
-        boolean updated = seqNoPrimaryTermAndIndex.compareAndSet(expectedValue, newValue);
+        boolean updated = seqNoPrimaryTermAndIndexHolder.compareAndSet(expectedValue, newValue);
         // This should never happen. We ONLY ever update this value if at initialization or we just finished updating the document
         // famous last words...
         if (updated == false) {
@@ -337,7 +337,7 @@ class ClientTransformIndexer extends TransformIndexer {
                 "[{}] Unexpected change to internal state detected, expected [{}], got [{}]",
                 transformConfig.getId(),
                 expectedValue,
-                seqNoPrimaryTermAndIndex.get()
+                seqNoPrimaryTermAndIndexHolder.get()
             );
             assert updated : "[" + getJobId() + "] unexpected change to seqNoPrimaryTermAndIndex.";
         }
@@ -345,7 +345,7 @@ class ClientTransformIndexer extends TransformIndexer {
 
     @Nullable
     SeqNoPrimaryTermAndIndex getSeqNoPrimaryTermAndIndex() {
-        return seqNoPrimaryTermAndIndex.get();
+        return seqNoPrimaryTermAndIndexHolder.get();
     }
 
     @Override
diff --git a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformIndexer.java b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformIndexer.java
index 3e3fad5ecc64..65e1458d37f0 100644
--- a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformIndexer.java
+++ b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformIndexer.java
@@ -321,8 +321,8 @@ public abstract class TransformIndexer extends AsyncTwoPhaseIndexer<TransformInd
             }
         }, listener::onFailure);
 
-        ActionListener<Map<String, String>> fieldMappingsListener = ActionListener.wrap(fieldMappings -> {
-            this.fieldMappings = fieldMappings;
+        ActionListener<Map<String, String>> fieldMappingsListener = ActionListener.wrap(mappings -> {
+            this.fieldMappings = mappings;
             configurationReadyListener.onResponse(null);
         }, listener::onFailure);
 
diff --git a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformTask.java b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformTask.java
index 82764baeb81c..778e2a34e304 100644
--- a/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformTask.java
+++ b/x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformTask.java
@@ -181,8 +181,8 @@ public class TransformTask extends AllocatedPersistentTask implements SchedulerE
             listener.onResponse(infoBuilder.build());
         }, listener::onFailure);
 
-        ClientTransformIndexer indexer = getIndexer();
-        if (indexer == null) {
+        ClientTransformIndexer transformIndexer = getIndexer();
+        if (transformIndexer == null) {
             transformsCheckpointService.getCheckpointingInfo(
                 parentTaskClient,
                 transform.getId(),
@@ -193,12 +193,12 @@ public class TransformTask extends AllocatedPersistentTask implements SchedulerE
             );
             return;
         }
-        indexer.getCheckpointProvider()
+        transformIndexer.getCheckpointProvider()
             .getCheckpointingInfo(
-                indexer.getLastCheckpoint(),
-                indexer.getNextCheckpoint(),
-                indexer.getPosition(),
-                indexer.getProgress(),
+                transformIndexer.getLastCheckpoint(),
+                transformIndexer.getNextCheckpoint(),
+                transformIndexer.getPosition(),
+                transformIndexer.getProgress(),
                 checkPointInfoListener
             );
     }
diff --git a/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerStateTests.java b/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerStateTests.java
index be5d4cda2bd1..39a7b239d1cb 100644
--- a/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerStateTests.java
+++ b/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerStateTests.java
@@ -614,7 +614,7 @@ public class TransformIndexerStateTests extends ESTestCase {
         AtomicReference<IndexerState> state,
         Consumer<String> failureConsumer,
         ThreadPool threadPool,
-        TransformAuditor auditor,
+        TransformAuditor transformAuditor,
         TransformIndexerPosition initialPosition,
         TransformIndexerStats jobStats,
         TransformContext context
@@ -624,7 +624,7 @@ public class TransformIndexerStateTests extends ESTestCase {
         TransformServices transformServices = new TransformServices(
             transformConfigManager,
             mock(TransformCheckpointService.class),
-            auditor,
+            transformAuditor,
             mock(SchedulerEngine.class)
         );
 
diff --git a/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerTests.java b/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerTests.java
index bbe9438286ce..c0018d26345c 100644
--- a/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerTests.java
+++ b/x-pack/plugin/transform/src/test/java/org/elasticsearch/xpack/transform/transforms/TransformIndexerTests.java
@@ -436,7 +436,7 @@ public class TransformIndexerTests extends ESTestCase {
         AtomicReference<IndexerState> state,
         Consumer<String> failureConsumer,
         ThreadPool threadPool,
-        TransformAuditor auditor,
+        TransformAuditor transformAuditor,
         TransformIndexerStats jobStats,
         TransformContext context
     ) {
@@ -445,7 +445,7 @@ public class TransformIndexerTests extends ESTestCase {
         TransformServices transformServices = new TransformServices(
             transformConfigManager,
             mock(TransformCheckpointService.class),
-            auditor,
+            transformAuditor,
             mock(SchedulerEngine.class)
         );