Replace NOT operator with explicit false check (#67817)

We have an in-house rule to compare explicitly against `false` instead
of using the logical not operator (`!`). However, this hasn't
historically been enforced, meaning that there are many violations in
the source at present.

We now have a Checkstyle rule that can detect these cases, but before we
can turn it on, we need to fix the existing violations. This is being
done over a series of PRs, since there are a lot to fix.

buildSrc/src/main/groovy/org/elasticsearch/gradle/NoticeTask.groovy

@@ -124,7 +124,7 @@ class NoticeTask extends DefaultTask {
                     if (line.contains('*/')) {
                         inNotice = false
 
-                        if (!isPackageInfo) {
+                        if (isPackageInfo == false) {
                             break
                         }
                     } else if (inNotice) {

buildSrc/src/main/java/org/elasticsearch/gradle/ElasticsearchDistribution.java

@@ -105,7 +105,7 @@ public class ElasticsearchDistribution implements Buildable, Iterable<File> {
     private final Property<Boolean> failIfUnavailable;
     private final Configuration extracted;
     private Action<ElasticsearchDistribution> distributionFinalizer;
-    private boolean froozen = false;
+    private boolean frozen = false;
 
     ElasticsearchDistribution(
         String name,
@@ -207,10 +207,10 @@ public class ElasticsearchDistribution implements Buildable, Iterable<File> {
      * runs distribution finalizer logic.
      */
     public ElasticsearchDistribution maybeFreeze() {
-        if (!froozen) {
+        if (frozen == false) {
             finalizeValues();
             distributionFinalizer.execute(this);
-            froozen = true;
+            frozen = true;
         }
         return this;
     }

buildSrc/src/main/java/org/elasticsearch/gradle/internal/InternalDistributionDownloadPlugin.java

@@ -83,7 +83,7 @@ public class InternalDistributionDownloadPlugin implements InternalPlugin {
         resolutions.register("bwc", distributionResolution -> distributionResolution.setResolver((project, distribution) -> {
             BwcVersions.UnreleasedVersionInfo unreleasedInfo = bwcVersions.unreleasedInfo(Version.fromString(distribution.getVersion()));
             if (unreleasedInfo != null) {
-                if (!distribution.getBundledJdk()) {
+                if (distribution.getBundledJdk() == false) {
                     throw new GradleException(
                         "Configuring a snapshot bwc distribution ('"
                             + distribution.getName()

buildSrc/src/main/java/org/elasticsearch/gradle/internal/precommit/FilePermissionsTask.java

@@ -106,7 +106,7 @@ public abstract class FilePermissionsTask extends DefaultTask {
             .map(file -> "Source file is executable: " + file)
             .collect(Collectors.toList());
 
-        if (!failures.isEmpty()) {
+        if (failures.isEmpty() == false) {
             throw new GradleException("Found invalid file permissions:\n" + String.join("\n", failures));
         }
 

buildSrc/src/main/java/org/elasticsearch/gradle/testclusters/ElasticsearchNode.java

@@ -1235,7 +1235,7 @@ public class ElasticsearchNode implements TestClusterConfiguration {
             String content = new String(Files.readAllBytes(jvmOptions));
             Map<String, String> expansions = jvmOptionExpansions();
             for (String origin : expansions.keySet()) {
-                if (!content.contains(origin)) {
+                if (content.contains(origin) == false) {
                     throw new IOException("template property " + origin + " not found in template.");
                 }
                 content = content.replace(origin, expansions.get(origin));

buildSrc/src/main/java/org/elasticsearch/gradle/util/FileUtils.java

@@ -39,13 +39,13 @@ public final class FileUtils {
             return;
         }
 
-        if (dir.exists() && !dir.isDirectory()) {
+        if (dir.exists() && dir.isDirectory() == false) {
             throw new UncheckedIOException(String.format("Cannot create directory '%s' as it already exists, but is not a directory", dir));
         }
 
         List<File> toCreate = new LinkedList<File>();
         File parent = dir.getParentFile();
-        while (!parent.exists()) {
+        while (parent.exists() == false) {
             toCreate.add(parent);
             parent = parent.getParentFile();
         }
@@ -55,7 +55,7 @@ public final class FileUtils {
                 continue;
             }
             File parentDirToCreateParent = parentDirToCreate.getParentFile();
-            if (!parentDirToCreateParent.isDirectory()) {
+            if (parentDirToCreateParent.isDirectory() == false) {
                 throw new UncheckedIOException(
                     String.format(
                         "Cannot create parent directory '%s' when creating directory '%s' as '%s' is not a directory",
@@ -65,13 +65,13 @@ public final class FileUtils {
                     )
                 );
             }
-            if (!parentDirToCreate.mkdir() && !parentDirToCreate.isDirectory()) {
+            if (parentDirToCreate.mkdir() == false && parentDirToCreate.isDirectory() == false) {
                 throw new UncheckedIOException(
                     String.format("Failed to create parent directory '%s' when creating directory '%s'", parentDirToCreate, dir)
                 );
             }
         }
-        if (!dir.mkdir() && !dir.isDirectory()) {
+        if (dir.mkdir() == false && dir.isDirectory() == false) {
             throw new UncheckedIOException(String.format("Failed to create directory '%s'", dir));
         }
     }

buildSrc/src/main/resources/checkstyle_ide_fragment.xml

@@ -15,7 +15,7 @@
         <property name="tokens" value="EXPR"/>
         <property name="limitedTokens" value="LNOT"/>
         <property name="maximumNumber" value="0"/>
-        <property name="maximumDepth" value="1"/>
+        <property name="maximumDepth" value="2"/>
         <message
             key="descendant.token.max"
             value="Do not negate boolean expressions with '!', but check explicitly with '== false' as it is more explicit"/>

client/benchmark/src/main/java/org/elasticsearch/client/benchmark/metrics/MetricsCalculator.java

@@ -37,7 +37,7 @@ public final class MetricsCalculator {
         Map<String, List<Sample>> samplesPerOperation = new HashMap<>();
 
         for (Sample sample : samples) {
-            if (!samplesPerOperation.containsKey(sample.getOperation())) {
+            if (samplesPerOperation.containsKey(sample.getOperation()) == false) {
                 samplesPerOperation.put(sample.getOperation(), new ArrayList<>());
             }
             samplesPerOperation.get(sample.getOperation()).add(sample);

client/rest-high-level/src/main/java/org/elasticsearch/client/IngestRequestConverters.java

@@ -78,7 +78,7 @@ final class IngestRequestConverters {
 
     static Request simulatePipeline(SimulatePipelineRequest simulatePipelineRequest) throws IOException {
         RequestConverters.EndpointBuilder builder = new RequestConverters.EndpointBuilder().addPathPartAsIs("_ingest/pipeline");
-        if (simulatePipelineRequest.getId() != null && !simulatePipelineRequest.getId().isEmpty()) {
+        if (simulatePipelineRequest.getId() != null && simulatePipelineRequest.getId().isEmpty() == false) {
             builder.addPathPart(simulatePipelineRequest.getId());
         }
         builder.addPathPartAsIs("_simulate");

client/rest-high-level/src/main/java/org/elasticsearch/client/ccr/GetAutoFollowPatternResponse.java

@@ -158,7 +158,7 @@ public final class GetAutoFollowPatternResponse {
         public boolean equals(Object o) {
             if (this == o) return true;
             if (o == null || getClass() != o.getClass()) return false;
-            if (!super.equals(o)) return false;
+            if (super.equals(o) == false) return false;
             Pattern pattern = (Pattern) o;
             return Objects.equals(remoteCluster, pattern.remoteCluster) &&
                 Objects.equals(leaderIndexPatterns, pattern.leaderIndexPatterns) &&

client/rest-high-level/src/main/java/org/elasticsearch/client/ccr/PutAutoFollowPatternRequest.java

@@ -81,7 +81,7 @@ public final class PutAutoFollowPatternRequest extends FollowConfig implements V
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
         PutAutoFollowPatternRequest that = (PutAutoFollowPatternRequest) o;
         return Objects.equals(name, that.name) &&
             Objects.equals(remoteCluster, that.remoteCluster) &&

client/rest-high-level/src/main/java/org/elasticsearch/client/ccr/PutFollowRequest.java

@@ -79,7 +79,7 @@ public final class PutFollowRequest extends FollowConfig implements Validatable,
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
         PutFollowRequest that = (PutFollowRequest) o;
         return Objects.equals(waitForActiveShards, that.waitForActiveShards) &&
             Objects.equals(remoteCluster, that.remoteCluster) &&

client/rest-high-level/src/main/java/org/elasticsearch/client/ccr/ResumeFollowRequest.java

@@ -50,7 +50,7 @@ public final class ResumeFollowRequest extends FollowConfig implements Validatab
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
         ResumeFollowRequest that = (ResumeFollowRequest) o;
         return Objects.equals(followerIndex, that.followerIndex);
     }

client/rest-high-level/src/main/java/org/elasticsearch/client/core/MultiTermVectorsResponse.java

@@ -64,7 +64,7 @@ public class MultiTermVectorsResponse {
     @Override
     public boolean equals(Object obj) {
         if (this == obj) return true;
-        if (!(obj instanceof MultiTermVectorsResponse)) return false;
+        if ((obj instanceof MultiTermVectorsResponse) == false) return false;
         MultiTermVectorsResponse other = (MultiTermVectorsResponse) obj;
         return Objects.equals(responses, other.responses);
     }

client/rest-high-level/src/main/java/org/elasticsearch/client/core/TermVectorsResponse.java

@@ -23,14 +23,15 @@ import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.xcontent.ConstructingObjectParser;
 import org.elasticsearch.common.xcontent.XContentParser;
-import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constructorArg;
-import static org.elasticsearch.common.xcontent.ConstructingObjectParser.optionalConstructorArg;
 
 import java.util.Collections;
-import java.util.List;
 import java.util.Comparator;
+import java.util.List;
 import java.util.Objects;
 
+import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constructorArg;
+import static org.elasticsearch.common.xcontent.ConstructingObjectParser.optionalConstructorArg;
+
 public class TermVectorsResponse {
     private final String index;
     private final String id;
@@ -127,7 +128,7 @@ public class TermVectorsResponse {
     @Override
     public boolean equals(Object obj) {
         if (this == obj) return true;
-        if (!(obj instanceof TermVectorsResponse)) return false;
+        if ((obj instanceof TermVectorsResponse) == false) return false;
         TermVectorsResponse other = (TermVectorsResponse) obj;
         return index.equals(other.index)
             && Objects.equals(id, other.id)
@@ -203,7 +204,7 @@ public class TermVectorsResponse {
         @Override
         public boolean equals(Object obj) {
             if (this == obj) return true;
-            if (!(obj instanceof TermVector)) return false;
+            if ((obj instanceof TermVector) == false) return false;
             TermVector other = (TermVector) obj;
             return fieldName.equals(other.fieldName)
                 && Objects.equals(fieldStatistics, other.fieldStatistics)
@@ -267,7 +268,7 @@ public class TermVectorsResponse {
             @Override
             public boolean equals(Object obj) {
                 if (this == obj) return true;
-                if (!(obj instanceof FieldStatistics)) return false;
+                if ((obj instanceof FieldStatistics) == false) return false;
                 FieldStatistics other = (FieldStatistics) obj;
                 return docCount == other.docCount
                     && sumDocFreq == other.sumDocFreq
@@ -374,7 +375,7 @@ public class TermVectorsResponse {
             @Override
             public boolean equals(Object obj) {
                 if (this == obj) return true;
-                if (!(obj instanceof Term)) return false;
+                if ((obj instanceof Term) == false) return false;
                 Term other = (Term) obj;
                 return term.equals(other.term)
                     && termFreq == other.termFreq
@@ -456,7 +457,7 @@ public class TermVectorsResponse {
             @Override
             public boolean equals(Object obj) {
                 if (this == obj) return true;
-                if (!(obj instanceof Token)) return false;
+                if ((obj instanceof Token) == false) return false;
                 Token other = (Token) obj;
                 return Objects.equals(startOffset, other.startOffset)
                     && Objects.equals(endOffset,other.endOffset)

client/rest-high-level/src/main/java/org/elasticsearch/client/graph/Connection.java

@@ -179,9 +179,9 @@ public class Connection {
 
             ConnectionId vertexId = (ConnectionId) o;
 
-            if (source != null ? !source.equals(vertexId.source) : vertexId.source != null)
+            if (source != null ? source.equals(vertexId.source) == false : vertexId.source != null)
                 return false;
-            if (target != null ? !target.equals(vertexId.target) : vertexId.target != null)
+            if (target != null ? target.equals(vertexId.target) == false : vertexId.target != null)
                 return false;
 
             return true;

client/rest-high-level/src/main/java/org/elasticsearch/client/graph/Vertex.java

@@ -237,9 +237,9 @@ public class Vertex implements ToXContentFragment {
 
             VertexId vertexId = (VertexId) o;
 
-            if (field != null ? !field.equals(vertexId.field) : vertexId.field != null)
+            if (field != null ? field.equals(vertexId.field) == false : vertexId.field != null)
                 return false;
-            if (term != null ? !term.equals(vertexId.term) : vertexId.term != null)
+            if (term != null ? term.equals(vertexId.term) == false : vertexId.term != null)
                 return false;
 
             return true;

client/rest-high-level/src/main/java/org/elasticsearch/client/ilm/GetLifecyclePolicyResponse.java

@@ -63,7 +63,7 @@ public class GetLifecyclePolicyResponse implements ToXContentObject {
         ensureExpectedToken(XContentParser.Token.START_OBJECT, parser.currentToken(), parser);
         parser.nextToken();
 
-        while (!parser.isClosed()) {
+        while (parser.isClosed() == false) {
             if (parser.currentToken() == XContentParser.Token.START_OBJECT) {
                 String policyName = parser.currentName();
                 LifecyclePolicyMetadata policyDefinion = LifecyclePolicyMetadata.parse(parser, policyName);

client/rest-high-level/src/main/java/org/elasticsearch/client/indices/GetFieldMappingsResponse.java

@@ -157,7 +157,7 @@ public class GetFieldMappingsResponse {
         @Override
         public boolean equals(Object o) {
             if (this == o) return true;
-            if (!(o instanceof FieldMappingMetadata)) return false;
+            if ((o instanceof FieldMappingMetadata) == false) return false;
             FieldMappingMetadata that = (FieldMappingMetadata) o;
             return Objects.equals(fullName, that.fullName) && Objects.equals(source, that.source);
         }
@@ -177,7 +177,7 @@ public class GetFieldMappingsResponse {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof GetFieldMappingsResponse)) return false;
+        if ((o instanceof GetFieldMappingsResponse) == false) return false;
         GetFieldMappingsResponse that = (GetFieldMappingsResponse) o;
         return Objects.equals(mappings, that.mappings);
     }

client/rest-high-level/src/main/java/org/elasticsearch/client/indices/GetIndexResponse.java

@@ -216,7 +216,7 @@ public class GetIndexResponse {
         ensureExpectedToken(Token.START_OBJECT, parser.currentToken(), parser);
         parser.nextToken();
 
-        while (!parser.isClosed()) {
+        while (parser.isClosed() == false) {
             if (parser.currentToken() == Token.START_OBJECT) {
                 // we assume this is an index entry
                 String indexName = parser.currentName();

client/rest-high-level/src/main/java/org/elasticsearch/client/indices/ResizeResponse.java

@@ -64,7 +64,7 @@ public class ResizeResponse extends ShardsAcknowledgedResponse {
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
         ResizeResponse that = (ResizeResponse) o;
         return Objects.equals(index, that.index);
     }

client/rest-high-level/src/main/java/org/elasticsearch/client/license/PutLicenseResponse.java

@@ -136,7 +136,7 @@ public final class PutLicenseResponse {
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
         PutLicenseResponse that = (PutLicenseResponse) o;
 
         return status == that.status &&

client/rest-high-level/src/main/java/org/elasticsearch/client/security/GetUsersRequest.java

@@ -46,7 +46,7 @@ public class GetUsersRequest implements Validatable {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof GetUsersRequest)) return false;
+        if ((o instanceof GetUsersRequest) == false) return false;
         GetUsersRequest that = (GetUsersRequest) o;
         return Objects.equals(usernames, that.usernames);
     }

client/rest-high-level/src/main/java/org/elasticsearch/client/security/GetUsersResponse.java

@@ -84,7 +84,7 @@ public class GetUsersResponse {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof GetUsersResponse)) return false;
+        if ((o instanceof GetUsersResponse) == false) return false;
         GetUsersResponse that = (GetUsersResponse) o;
         return Objects.equals(users, that.users);
     }

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/CancelTasksRequest.java

@@ -88,7 +88,7 @@ public class CancelTasksRequest implements Validatable {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof CancelTasksRequest)) return false;
+        if ((o instanceof CancelTasksRequest) == false) return false;
         CancelTasksRequest that = (CancelTasksRequest) o;
         return Objects.equals(getNodes(), that.getNodes()) &&
             Objects.equals(getActions(), that.getActions()) &&

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/ElasticsearchException.java

@@ -200,7 +200,7 @@ public class ElasticsearchException {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof ElasticsearchException)) return false;
+        if ((o instanceof ElasticsearchException) == false) return false;
         ElasticsearchException that = (ElasticsearchException) o;
         return Objects.equals(getMsg(), that.getMsg()) &&
             Objects.equals(getCause(), that.getCause()) &&

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/GetTaskRequest.java

@@ -77,7 +77,7 @@ public class GetTaskRequest implements Validatable {
     @Override
     public Optional<ValidationException> validate() {
         final ValidationException validationException = new ValidationException();
-        if (timeout != null && !waitForCompletion) {
+        if (timeout != null && waitForCompletion == false) {
             validationException.addValidationError("Timeout settings are only accepted if waitForCompletion is also set");
         }
         if (validationException.validationErrors().isEmpty()) {

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/ListTasksResponse.java

@@ -110,7 +110,7 @@ public class ListTasksResponse {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof ListTasksResponse)) return false;
+        if ((o instanceof ListTasksResponse) == false) return false;
         ListTasksResponse response = (ListTasksResponse) o;
         return nodesInfoData.equals(response.nodesInfoData) &&
             Objects.equals

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/NodeData.java

@@ -124,7 +124,7 @@ class NodeData {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof NodeData)) return false;
+        if ((o instanceof NodeData) == false) return false;
         NodeData nodeData = (NodeData) o;
         return Objects.equals(getNodeId(), nodeData.getNodeId()) &&
             Objects.equals(getName(), nodeData.getName()) &&

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/TaskGroup.java

@@ -54,7 +54,7 @@ public class TaskGroup {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof TaskGroup)) return false;
+        if ((o instanceof TaskGroup) == false) return false;
         TaskGroup taskGroup = (TaskGroup) o;
         return Objects.equals(task, taskGroup.task) &&
             Objects.equals(getChildTasks(), taskGroup.getChildTasks());

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/TaskId.java

@@ -78,7 +78,7 @@ public class TaskId {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof TaskId)) return false;
+        if ((o instanceof TaskId) == false) return false;
         TaskId taskId = (TaskId) o;
         return getId() == taskId.getId() &&
             Objects.equals(getNodeId(), taskId.getNodeId());

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/TaskInfo.java

@@ -153,7 +153,7 @@ public class TaskInfo {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof TaskInfo)) return false;
+        if ((o instanceof TaskInfo) == false) return false;
         TaskInfo taskInfo = (TaskInfo) o;
         return getStartTime() == taskInfo.getStartTime() &&
             getRunningTimeNanos() == taskInfo.getRunningTimeNanos() &&

client/rest-high-level/src/main/java/org/elasticsearch/client/tasks/TaskOperationFailure.java

@@ -63,7 +63,7 @@ public class TaskOperationFailure {
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (!(o instanceof TaskOperationFailure)) return false;
+        if ((o instanceof TaskOperationFailure) == false) return false;
         TaskOperationFailure that = (TaskOperationFailure) o;
         return getTaskId() == that.getTaskId() &&
             Objects.equals(getNodeId(), that.getNodeId()) &&

client/rest-high-level/src/main/java/org/elasticsearch/client/watcher/AckWatchRequest.java

@@ -57,7 +57,7 @@ public class AckWatchRequest implements Validatable {
             }
         }
 
-        if (!exception.validationErrors().isEmpty()) {
+        if (exception.validationErrors().isEmpty() == false) {
             throw exception;
         }
     }

client/rest-high-level/src/test/java/org/elasticsearch/client/IngestRequestConvertersTests.java

@@ -128,8 +128,9 @@ public class IngestRequestConvertersTests extends ESTestCase {
         Request expectedRequest = IngestRequestConverters.simulatePipeline(request);
         StringJoiner endpoint = new StringJoiner("/", "/", "");
         endpoint.add("_ingest/pipeline");
-        if (pipelineId != null && !pipelineId.isEmpty())
+        if (pipelineId != null && pipelineId.isEmpty() == false) {
             endpoint.add(pipelineId);
+        }
         endpoint.add("_simulate");
         Assert.assertEquals(endpoint.toString(), expectedRequest.getEndpoint());
         Assert.assertEquals(HttpPost.METHOD_NAME, expectedRequest.getMethod());

client/rest-high-level/src/test/java/org/elasticsearch/client/RequestConvertersTests.java

@@ -1509,7 +1509,7 @@ public class RequestConvertersTests extends ESTestCase {
         // Verify that the resulting REST request looks as expected.
         StringJoiner endpoint = new StringJoiner("/", "/", "");
         String joinedIndices = String.join(",", indices);
-        if (!joinedIndices.isEmpty()) {
+        if (joinedIndices.isEmpty() == false) {
             endpoint.add(joinedIndices);
         }
         endpoint.add("_field_caps");
@@ -1550,7 +1550,7 @@ public class RequestConvertersTests extends ESTestCase {
         // Verify that the resulting REST request looks as expected.
         StringJoiner endpoint = new StringJoiner("/", "/", "");
         String joinedIndices = String.join(",", indices);
-        if (!joinedIndices.isEmpty()) {
+        if (joinedIndices.isEmpty() == false) {
             endpoint.add(joinedIndices);
         }
         endpoint.add("_field_caps");

client/rest-high-level/src/test/java/org/elasticsearch/client/RestHighLevelClientTests.java

@@ -960,7 +960,7 @@ public class RestHighLevelClientTests extends ESTestCase {
                 method.getReturnType().getSimpleName(), equalTo("boolean"));
         } else {
             // It's acceptable for 404s to be represented as empty Optionals
-            if (!method.getReturnType().isAssignableFrom(Optional.class)) {
+            if (method.getReturnType().isAssignableFrom(Optional.class) == false) {
                 assertThat("the return type for method [" + method + "] is incorrect",
                     method.getReturnType().getSimpleName(), endsWith("Response"));
             }

client/rest-high-level/src/test/java/org/elasticsearch/client/ml/job/config/DetectionRuleTests.java

@@ -46,7 +46,7 @@ public class DetectionRuleTests extends AbstractXContentTestCase<DetectionRule>
         boolean hasScope = randomBoolean();
         boolean hasConditions = randomBoolean();
 
-        if (!hasScope && !hasConditions) {
+        if (hasScope == false && hasConditions == false) {
             // at least one of the two should be present
             if (randomBoolean()) {
                 hasScope = true;

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

@@ -73,7 +73,7 @@ public final class PreferHasAttributeNodeSelector implements NodeSelector {
 
                 List<String> values = attributes.get(key);
 
-                if (values == null || !values.contains(value)) {
+                if (values == null || values.contains(value) == false) {
                     nodeIterator.remove();
                 }
             }

distribution/tools/java-version-checker/src/main/java/org/elasticsearch/tools/java_version_checker/JavaVersion.java

@@ -29,7 +29,7 @@ public class JavaVersion {
     public static final List<Integer> JAVA_11 = parse("11");
 
     static List<Integer> parse(final String value) {
-        if (!value.matches("^0*[0-9]+(\\.[0-9]+)*$")) {
+        if (value.matches("^0*[0-9]+(\\.[0-9]+)*$") == false) {
             throw new IllegalArgumentException(value);
         }
 

distribution/tools/plugin-cli/src/main/java/org/elasticsearch/plugins/InstallPluginCommand.java

@@ -723,7 +723,7 @@ class InstallPluginCommand extends EnvironmentAwareCommand {
 
                 // be on the safe side: do not rely on that directories are always extracted
                 // before their children (although this makes sense, but is it guaranteed?)
-                if (!Files.isSymbolicLink(targetFile.getParent())) {
+                if (Files.isSymbolicLink(targetFile.getParent()) == false) {
                     Files.createDirectories(targetFile.getParent());
                 }
                 if (entry.isDirectory() == false) {

distribution/tools/plugin-cli/src/main/java/org/elasticsearch/plugins/RemovePluginCommand.java

@@ -136,7 +136,7 @@ class RemovePluginCommand extends EnvironmentAwareCommand {
 
         final Path pluginBinDir = env.binFile().resolve(pluginName);
         if (Files.exists(pluginBinDir)) {
-            if (!Files.isDirectory(pluginBinDir)) {
+            if (Files.isDirectory(pluginBinDir) == false) {
                 throw new UserException(ExitCodes.IO_ERROR, "bin dir for " + pluginName + " is not a directory");
             }
             try (Stream<Path> paths = Files.list(pluginBinDir)) {

libs/core/src/main/java/org/elasticsearch/bootstrap/JarHell.java

@@ -175,7 +175,7 @@ public class JarHell {
                 continue;
             }
             if (path.toString().endsWith(".jar")) {
-                if (!seenJars.add(path)) {
+                if (seenJars.add(path) == false) {
                     throw new IllegalStateException("jar hell!" + System.lineSeparator() +
                                                     "duplicate jar on classpath: " + path);
                 }
@@ -233,7 +233,7 @@ public class JarHell {
     }
 
     public static void checkVersionFormat(String targetVersion) {
-        if (!JavaVersion.isValid(targetVersion)) {
+        if (JavaVersion.isValid(targetVersion) == false) {
             throw new IllegalStateException(
                     String.format(
                             Locale.ROOT,

libs/core/src/main/java/org/elasticsearch/bootstrap/JavaVersion.java

@@ -54,7 +54,7 @@ public class JavaVersion implements Comparable<JavaVersion> {
     public static JavaVersion parse(String value) {
         Objects.requireNonNull(value);
         String prePart = null;
-        if (!isValid(value)) {
+        if (isValid(value) == false) {
             throw new IllegalArgumentException("Java version string [" + value + "] could not be parsed.");
         }
         List<Integer> version = new ArrayList<>();

libs/core/src/main/java/org/elasticsearch/common/Booleans.java

@@ -79,7 +79,7 @@ public final class Booleans {
         }
         int strLen = str.length();
         for (int i = 0; i < strLen; i++) {
-            if (!Character.isWhitespace(str.charAt(i))) {
+            if (Character.isWhitespace(str.charAt(i)) == false) {
                 return true;
             }
         }
@@ -128,7 +128,16 @@ public final class Booleans {
         if (value == null) {
             return defaultValue;
         }
-        return !(value.equals("false") || value.equals("0") || value.equals("off") || value.equals("no"));
+        switch (value) {
+            case "false":
+            case "0":
+            case "off":
+            case "no":
+                return false;
+
+            default:
+                return true;
+        }
     }
 
     /**
@@ -159,14 +168,14 @@ public final class Booleans {
             return text[offset] != '0';
         }
         if (length == 2) {
-            return !(text[offset] == 'n' && text[offset + 1] == 'o');
+            return (text[offset] == 'n' && text[offset + 1] == 'o') == false;
         }
         if (length == 3) {
-            return !(text[offset] == 'o' && text[offset + 1] == 'f' && text[offset + 2] == 'f');
+            return (text[offset] == 'o' && text[offset + 1] == 'f' && text[offset + 2] == 'f') == false;
         }
         if (length == 5) {
-            return !(text[offset] == 'f' && text[offset + 1] == 'a' && text[offset + 2] == 'l' && text[offset + 3] == 's' &&
+            return (text[offset] == 'f' && text[offset + 1] == 'a' && text[offset + 2] == 'l' && text[offset + 3] == 's' &&
-                text[offset + 4] == 'e');
+                text[offset + 4] == 'e') == false;
         }
         return true;
     }

libs/core/src/main/java/org/elasticsearch/common/collect/Tuple.java

@@ -48,8 +48,8 @@ public class Tuple<V1, V2> {
 
         Tuple<?, ?> tuple = (Tuple<?, ?>) o;
 
-        if (v1 != null ? !v1.equals(tuple.v1) : tuple.v1 != null) return false;
+        if (v1 != null ? v1.equals(tuple.v1) == false : tuple.v1 != null) return false;
-        if (v2 != null ? !v2.equals(tuple.v2) : tuple.v2 != null) return false;
+        if (v2 != null ? v2.equals(tuple.v2) == false : tuple.v2 != null) return false;
 
         return true;
     }

libs/core/src/main/java/org/elasticsearch/core/internal/io/IOUtils.java

@@ -200,7 +200,7 @@ public final class IOUtils {
      */
     public static void rm(final Path... locations) throws IOException {
         final LinkedHashMap<Path,Throwable> unremoved = rm(new LinkedHashMap<>(), locations);
-        if (!unremoved.isEmpty()) {
+        if (unremoved.isEmpty() == false) {
             final StringBuilder b = new StringBuilder("could not remove the following files (in the order of attempts):\n");
             for (final Map.Entry<Path,Throwable> kv : unremoved.entrySet()) {
                 b.append("   ")

libs/dissect/src/main/java/org/elasticsearch/dissect/DissectKey.java

@@ -174,13 +174,13 @@ public final class DissectKey {
 
         private static Modifier findModifier(String key) {
             Modifier modifier = Modifier.NONE;
-            if (key != null && !key.isEmpty()) {
+            if (key != null && key.isEmpty() == false) {
                 Matcher matcher = MODIFIER_PATTERN.matcher(key);
                 int matches = 0;
                 while (matcher.find()) {
                     Modifier priorModifier = modifier;
                     modifier = Modifier.fromString(matcher.group());
-                    if (++matches > 1 && !(APPEND.equals(priorModifier) && APPEND_WITH_ORDER.equals(modifier))) {
+                    if (++matches > 1 && (APPEND.equals(priorModifier) && APPEND_WITH_ORDER.equals(modifier)) == false) {
                         throw new DissectException.KeyParse(key, "multiple modifiers are not allowed.");
                     }
                 }

libs/dissect/src/main/java/org/elasticsearch/dissect/DissectParser.java

@@ -240,9 +240,9 @@ public final class DissectParser {
                             if (lookAheadMatches == delimiter.length) {
                                 //jump to the end of the match
                                 i += lookAheadMatches;
-                                if (!key.skipRightPadding()) {
+                                if (key.skipRightPadding() == false) {
                                     //progress the keys/delimiter if possible
-                                    if (!it.hasNext()) {
+                                    if (it.hasNext() == false) {
                                         break; //the while loop
                                     }
                                     dissectPair = it.next();
@@ -255,7 +255,7 @@ public final class DissectParser {
                             }
                         }
                         //progress the keys/delimiter if possible
-                        if (!it.hasNext()) {
+                        if (it.hasNext() == false) {
                             break; //the for loop
                         }
                         dissectPair = it.next();
@@ -272,7 +272,7 @@ public final class DissectParser {
             }
             //the last key, grab the rest of the input (unless consecutive delimiters already grabbed the last key)
             //and there is no trailing delimiter
-            if (!dissectMatch.fullyMatched() && delimiter.length == 0 ) {
+            if (dissectMatch.fullyMatched() == false && delimiter.length == 0 ) {
                 byte[] value = Arrays.copyOfRange(input, valueStart, input.length);
                 String valueString = new String(value, StandardCharsets.UTF_8);
                 dissectMatch.add(key, valueString);
@@ -280,7 +280,7 @@ public final class DissectParser {
         }
         Map<String, String> results = dissectMatch.getResults();
 
-        if (!dissectMatch.isValid(results)) {
+        if (dissectMatch.isValid(results) == false) {
             throw new DissectException.FindMatch(pattern, inputString);
         }
         return results;

libs/dissect/src/test/java/org/elasticsearch/dissect/DissectParserTests.java

@@ -326,7 +326,7 @@ public class DissectParserTests extends ESTestCase {
         while (tests.hasNext()) {
             JsonNode test = tests.next();
             boolean skip = test.path("skip").asBoolean();
-            if (!skip) {
+            if (skip == false) {
                 String name = test.path("name").asText();
                 logger.debug("Running Json specification: " + name);
                 String pattern = test.path("tok").asText();

libs/geo/src/main/java/org/elasticsearch/geometry/utils/WellKnownText.java

@@ -433,7 +433,7 @@ public class WellKnownText {
     private void closeLinearRingIfCoerced(ArrayList<Double> lats, ArrayList<Double> lons, ArrayList<Double> alts) {
         if (coerce && lats.isEmpty() == false && lons.isEmpty() == false) {
             int last = lats.size() - 1;
-            if (!lats.get(0).equals(lats.get(last)) || !lons.get(0).equals(lons.get(last)) ||
+            if (lats.get(0).equals(lats.get(last)) == false || lons.get(0).equals(lons.get(last)) == false ||
                 (alts.isEmpty() == false && !alts.get(0).equals(alts.get(last)))) {
                 lons.add(lons.get(0));
                 lats.add(lats.get(0));

libs/ssl-config/src/main/java/org/elasticsearch/common/ssl/DerParser.java

@@ -194,8 +194,9 @@ final class DerParser {
          * @return A parser for the construct.
          */
         public DerParser getParser() throws IOException {
-            if (!isConstructed())
+            if (isConstructed() == false) {
                 throw new IOException("Invalid DER: can't parse primitive entity"); //$NON-NLS-1$
+            }
 
             return new DerParser(value);
         }

libs/x-content/src/main/java/org/elasticsearch/common/xcontent/support/AbstractXContentParser.java

@@ -48,7 +48,7 @@ public abstract class AbstractXContentParser implements XContentParser {
     public static final boolean DEFAULT_NUMBER_COERCE_POLICY = true;
 
     private static void checkCoerceString(boolean coerce, Class<? extends Number> clazz) {
-        if (!coerce) {
+        if (coerce == false) {
             //Need to throw type IllegalArgumentException as current catch logic in
             //NumberFieldMapper.parseCreateField relies on this for "malformed" value detection
             throw new IllegalArgumentException(clazz.getSimpleName() + " value passed as String");
@@ -68,7 +68,7 @@ public abstract class AbstractXContentParser implements XContentParser {
     // If this behaviour is flagged as undesirable and any truncation occurs
     // then this method is called to trigger the"malformed" handling logic
     void ensureNumberConversion(boolean coerce, long result, Class<? extends Number> clazz) throws IOException {
-        if (!coerce) {
+        if (coerce == false) {
             double fullVal = doDoubleValue();
             if (result != fullVal) {
                 // Need to throw type IllegalArgumentException as current catch

modules/aggs-matrix-stats/src/main/java/org/elasticsearch/search/aggregations/matrix/stats/MatrixStatsAggregator.java

@@ -49,7 +49,7 @@ final class MatrixStatsAggregator extends MetricsAggregator {
     MatrixStatsAggregator(String name, Map<String, ValuesSource.Numeric> valuesSources, AggregationContext context,
                                  Aggregator parent, MultiValueMode multiValueMode, Map<String,Object> metadata) throws IOException {
         super(name, context, parent, metadata);
-        if (valuesSources != null && !valuesSources.isEmpty()) {
+        if (valuesSources != null && valuesSources.isEmpty() == false) {
             this.valuesSources = new NumericArrayValuesSource(valuesSources, multiValueMode);
             stats = context.bigArrays().newObjectArray(1);
         } else {

modules/aggs-matrix-stats/src/main/java/org/elasticsearch/search/aggregations/support/ArrayValuesSourceParser.java

@@ -88,7 +88,7 @@ public abstract class ArrayValuesSourceParser<VS extends ValuesSource> implement
                     throw new ParsingException(parser.getTokenLocation(),
                         "Unexpected token " + token + " [" + currentFieldName + "] in [" + aggregationName + "]. " +
                             "Multi-field aggregations do not support scripts.");
-                } else if (!token(aggregationName, currentFieldName, token, parser, otherOptions)) {
+                } else if (token(aggregationName, currentFieldName, token, parser, otherOptions) == false) {
                     throw new ParsingException(parser.getTokenLocation(),
                         "Unexpected token " + token + " [" + currentFieldName + "] in [" + aggregationName + "].");
                 }
@@ -103,7 +103,7 @@ public abstract class ArrayValuesSourceParser<VS extends ValuesSource> implement
                         "Unexpected token " + token + " [" + currentFieldName + "] in [" + aggregationName + "]. " +
                             "Multi-field aggregations do not support scripts.");
 
-                } else if (!token(aggregationName, currentFieldName, token, parser, otherOptions)) {
+                } else if (token(aggregationName, currentFieldName, token, parser, otherOptions) == false) {
                     throw new ParsingException(parser.getTokenLocation(),
                         "Unexpected token " + token + " [" + currentFieldName + "] in [" + aggregationName + "].");
                 }
@@ -122,11 +122,11 @@ public abstract class ArrayValuesSourceParser<VS extends ValuesSource> implement
                                 "Unexpected token " + token + " [" + currentFieldName + "] in [" + aggregationName + "].");
                         }
                     }
-                } else if (!token(aggregationName, currentFieldName, token, parser, otherOptions)) {
+                } else if (token(aggregationName, currentFieldName, token, parser, otherOptions) == false) {
                     throw new ParsingException(parser.getTokenLocation(),
                         "Unexpected token " + token + " [" + currentFieldName + "] in [" + aggregationName + "].");
                 }
-            } else if (!token(aggregationName, currentFieldName, token, parser, otherOptions)) {
+            } else if (token(aggregationName, currentFieldName, token, parser, otherOptions) == false) {
                 throw new ParsingException(parser.getTokenLocation(),
                     "Unexpected token " + token + " [" + currentFieldName + "] in [" + aggregationName + "].");
             }

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/MappingCharFilterFactory.java

@@ -64,8 +64,9 @@ public class MappingCharFilterFactory extends AbstractCharFilterFactory implemen
     private void parseRules(List<String> rules, NormalizeCharMap.Builder map) {
         for (String rule : rules) {
             Matcher m = rulePattern.matcher(rule);
-            if (!m.find())
+            if (m.find() == false) {
                 throw new RuntimeException("Invalid Mapping Rule : [" + rule + "]");
+            }
             String lhs = parseString(m.group(1).trim());
             String rhs = parseString(m.group(2).trim());
             if (lhs == null || rhs == null)

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/NGramTokenizerFactory.java

@@ -56,7 +56,7 @@ public class NGramTokenizerFactory extends AbstractTokenizerFactory {
         matchers.put("symbol", CharMatcher.Basic.SYMBOL);
         // Populate with unicode categories from java.lang.Character
         for (Field field : Character.class.getFields()) {
-            if (!field.getName().startsWith("DIRECTIONALITY")
+            if (field.getName().startsWith("DIRECTIONALITY") == false
                     && Modifier.isPublic(field.getModifiers())
                     && Modifier.isStatic(field.getModifiers())
                     && field.getType() == byte.class) {

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/PatternReplaceCharFilterFactory.java

@@ -39,7 +39,7 @@ public class PatternReplaceCharFilterFactory extends AbstractCharFilterFactory i
         super(indexSettings, name);
 
         String sPattern = settings.get("pattern");
-        if (!Strings.hasLength(sPattern)) {
+        if (Strings.hasLength(sPattern) == false) {
             throw new IllegalArgumentException("pattern is missing for [" + name + "] char filter of type 'pattern_replace'");
         }
         pattern = Regex.compile(sPattern, settings.get("flags"));

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/UniqueTokenFilter.java

@@ -71,7 +71,7 @@ class UniqueTokenFilter extends TokenFilter {
             System.arraycopy(term, 0, saved, 0, length);
             previous.add(saved);
 
-            if (!duplicate) {
+            if (duplicate == false) {
                 return true;
             }
         }

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/WordDelimiterTokenFilterFactory.java

@@ -126,8 +126,9 @@ public class WordDelimiterTokenFilterFactory extends AbstractTokenFilterFactory
         SortedMap<Character, Byte> typeMap = new TreeMap<>();
         for (String rule : rules) {
             Matcher m = typePattern.matcher(rule);
-            if (!m.find())
+            if (m.find() == false) {
                 throw new RuntimeException("Invalid Mapping Rule : [" + rule + "]");
+            }
             String lhs = parseString(m.group(1).trim());
             Byte rhs = parseType(m.group(2).trim());
             if (lhs.length() != 1)

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/ConvertProcessor.java

@@ -102,7 +102,7 @@ public final class ConvertProcessor extends AbstractProcessor {
         }, AUTO {
             @Override
             public Object convert(Object value) {
-                if (!(value instanceof String)) {
+                if ((value instanceof String) == false) {
                    return value;
                 }
                 try {

modules/ingest-user-agent/src/main/java/org/elasticsearch/ingest/useragent/UserAgentParser.java

@@ -238,7 +238,7 @@ final class UserAgentParser {
           String name = null, major = null, minor = null, patch = null, build = null;
           Matcher matcher = pattern.matcher(agentString);
 
-          if (!matcher.find()) {
+          if (matcher.find() == false) {
             return null;
           }
 

modules/lang-expression/src/main/java/org/elasticsearch/script/expression/DateMethodValueSource.java

@@ -75,7 +75,7 @@ class DateMethodValueSource extends FieldDataValueSource {
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
 
         DateMethodValueSource that = (DateMethodValueSource) o;
 

modules/lang-expression/src/main/java/org/elasticsearch/script/expression/DateObjectValueSource.java

@@ -77,7 +77,7 @@ class DateObjectValueSource extends FieldDataValueSource {
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
 
         DateObjectValueSource that = (DateObjectValueSource) o;
         return methodName.equals(that.methodName);

modules/lang-expression/src/main/java/org/elasticsearch/script/expression/ExpressionScriptEngine.java

@@ -445,7 +445,7 @@ public class ExpressionScriptEngine implements ScriptEngine {
                     dateAccessor = true;
                 }
             }
-            if (!dateAccessor) {
+            if (dateAccessor == false) {
                 throw new IllegalArgumentException(
                     "Variable [" + variable + "] does not follow an allowed format of either doc['field'] or doc['field'].method()"
                 );

modules/lang-expression/src/main/java/org/elasticsearch/script/expression/FieldDataValueSource.java

@@ -49,7 +49,7 @@ class FieldDataValueSource extends FieldDataBasedDoubleValuesSource {
 
         FieldDataValueSource that = (FieldDataValueSource) o;
 
-        if (!fieldData.equals(that.fieldData)) return false;
+        if (fieldData.equals(that.fieldData) == false) return false;
         return multiValueMode == that.multiValueMode;
 
     }

modules/lang-expression/src/main/java/org/elasticsearch/script/expression/GeoLongitudeValueSource.java

@@ -64,7 +64,7 @@ final class GeoLongitudeValueSource extends FieldDataBasedDoubleValuesSource {
         if (obj == null) return false;
         if (getClass() != obj.getClass()) return false;
         GeoLongitudeValueSource other = (GeoLongitudeValueSource) obj;
-        if (!fieldData.equals(other.fieldData)) return false;
+        if (fieldData.equals(other.fieldData) == false) return false;
         return true;
     }
 

modules/lang-painless/src/main/java/org/elasticsearch/painless/Def.java

@@ -93,7 +93,7 @@ public final class Def {
         static int getArrayLength(final Object[] array)  { return array.length; }
 
         static MethodHandle arrayLengthGetter(Class<?> arrayType) {
-            if (!arrayType.isArray()) {
+            if (arrayType.isArray() == false) {
                 throw new IllegalArgumentException("type must be an array");
             }
             return (ARRAY_TYPE_MH_MAPPING.containsKey(arrayType)) ?
@@ -622,7 +622,7 @@ public final class Def {
         }
 
         static MethodHandle newIterator(Class<?> arrayType) {
-            if (!arrayType.isArray()) {
+            if (arrayType.isArray() == false) {
                 throw new IllegalArgumentException("type must be an array");
             }
             return (ARRAY_TYPE_MH_MAPPING.containsKey(arrayType)) ?
@@ -1269,7 +1269,7 @@ public final class Def {
         static int normalizeIndex(final Object[] array, final int index) { return index >= 0 ? index : index + array.length; }
 
         static MethodHandle arrayIndexNormalizer(Class<?> arrayType) {
-            if (!arrayType.isArray()) {
+            if (arrayType.isArray() == false) {
                 throw new IllegalArgumentException("type must be an array");
             }
             return (ARRAY_TYPE_MH_MAPPING.containsKey(arrayType)) ?

modules/lang-painless/src/main/java/org/elasticsearch/painless/MethodWriter.java

@@ -244,7 +244,7 @@ public final class MethodWriter extends GeneratorAdapter {
         if (from != boolean.class && from.isPrimitive() && to != boolean.class && to.isPrimitive()) {
             cast(getType(from), getType(to));
         } else {
-            if (!to.isAssignableFrom(from)) {
+            if (to.isAssignableFrom(from) == false) {
                 checkCast(getType(to));
             }
         }
@@ -357,7 +357,7 @@ public final class MethodWriter extends GeneratorAdapter {
                 // so we don't need a special NPE guard.
                 // otherwise, we need to allow nulls for possible string concatenation.
                 boolean hasPrimitiveArg = lhs.isPrimitive() || rhs.isPrimitive();
-                if (!hasPrimitiveArg) {
+                if (hasPrimitiveArg == false) {
                     flags |= DefBootstrap.OPERATOR_ALLOWS_NULL;
                 }
                 invokeDefCall("add", methodType, DefBootstrap.BINARY_OPERATOR, flags);
@@ -466,7 +466,7 @@ public final class MethodWriter extends GeneratorAdapter {
 
     @Override
     public void endMethod() {
-        if (stringConcatArgs != null && !stringConcatArgs.isEmpty()) {
+        if (stringConcatArgs != null && stringConcatArgs.isEmpty() == false) {
             throw new IllegalStateException("String concat bytecode not completed.");
         }
         super.endMethod();

modules/lang-painless/src/main/java/org/elasticsearch/painless/PainlessScript.java

@@ -89,7 +89,7 @@ public interface PainlessScript {
                 }
                 break;
             // but filter our own internal stacks (e.g. indy bootstrap)
-            } else if (!shouldFilter(element)) {
+            } else if (shouldFilter(element) == false) {
                 scriptStack.add(element.toString());
             }
         }

modules/lang-painless/src/main/java/org/elasticsearch/painless/PainlessScriptEngine.java

@@ -459,7 +459,7 @@ public final class PainlessScriptEngine implements ScriptEngine {
                 throw new IllegalArgumentException("[painless.regex.limit-factor] can only be set on node startup.");
             }
 
-            if (!copy.isEmpty()) {
+            if (copy.isEmpty() == false) {
                 throw new IllegalArgumentException("Unrecognized compile-time parameter(s): " + copy);
             }
         }

modules/lang-painless/src/main/java/org/elasticsearch/painless/phase/DefaultIRTreeToASMBytesPhase.java

@@ -1348,7 +1348,7 @@ public class DefaultIRTreeToASMBytesPhase implements IRTreeVisitor<WriteScope> {
         PainlessMethod getterPainlessMethod = irDotSubShortcutNode.getDecorationValue(IRDMethod.class);
         methodWriter.invokeMethodCall(getterPainlessMethod);
 
-        if (!getterPainlessMethod.returnType.equals(getterPainlessMethod.javaMethod.getReturnType())) {
+        if (getterPainlessMethod.returnType.equals(getterPainlessMethod.javaMethod.getReturnType()) == false) {
             methodWriter.checkCast(MethodWriter.getType(getterPainlessMethod.returnType));
         }
     }

modules/parent-join/src/internalClusterTest/java/org/elasticsearch/join/query/ChildQuerySearchIT.java

@@ -294,7 +294,7 @@ public class ChildQuerySearchIT extends ParentChildTestCase {
             String childId = "c" + i;
             builders.add(createIndexRequest("test", "child", childId, previousParentId, "c_field", childId));
 
-            if (!parentToChildren.containsKey(previousParentId)) {
+            if (parentToChildren.containsKey(previousParentId) == false) {
                 parentToChildren.put(previousParentId, new HashSet<>());
             }
             assertThat(parentToChildren.get(previousParentId).add(childId), is(true));

modules/parent-join/src/main/java/org/elasticsearch/join/query/HasChildQueryBuilder.java

@@ -406,9 +406,9 @@ public class HasChildQueryBuilder extends AbstractQueryBuilder<HasChildQueryBuil
 
             if (minChildren != that.minChildren) return false;
             if (maxChildren != that.maxChildren) return false;
-            if (!toQuery.equals(that.toQuery)) return false;
+            if (toQuery.equals(that.toQuery) == false) return false;
-            if (!innerQuery.equals(that.innerQuery)) return false;
+            if (innerQuery.equals(that.innerQuery) == false) return false;
-            if (!joinField.equals(that.joinField)) return false;
+            if (joinField.equals(that.joinField) == false) return false;
             return scoreMode == that.scoreMode;
         }
 

modules/percolator/src/main/java/org/elasticsearch/percolator/PercolateQueryBuilder.java

@@ -455,7 +455,7 @@ public class PercolateQueryBuilder extends AbstractQueryBuilder<PercolateQueryBu
             throw new QueryShardException(context, "field [" + field + "] does not exist");
         }
 
-        if (!(fieldType instanceof PercolatorFieldMapper.PercolatorFieldType)) {
+        if ((fieldType instanceof PercolatorFieldMapper.PercolatorFieldType) == false) {
             throw new QueryShardException(context, "expected field [" + field +
                 "] to be of type [percolator], but is of type [" + fieldType.typeName() + "]");
         }

modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractAsyncBulkByScrollAction.java

@@ -122,7 +122,7 @@ public abstract class AbstractAsyncBulkByScrollAction<Request extends AbstractBu
         this.task = task;
         this.scriptService = scriptService;
         this.sslConfig = sslConfig;
-        if (!task.isWorker()) {
+        if (task.isWorker() == false) {
             throw new IllegalArgumentException("Given task [" + task.getId() + "] must have a child worker");
         }
         this.worker = task.getWorkerState();

modules/transport-netty4/src/internalClusterTest/java/org/elasticsearch/transport/netty4/Netty4TransportPublishAddressIT.java

@@ -52,7 +52,7 @@ public class Netty4TransportPublishAddressIT extends ESNetty4IntegTestCase {
     }
 
     public void testDifferentPorts() throws Exception {
-        if (!NetworkUtils.SUPPORTS_V6) {
+        if (NetworkUtils.SUPPORTS_V6 == false) {
             return;
         }
         logger.info("--> starting a node on ipv4 only");

modules/transport-netty4/src/main/java/org/elasticsearch/http/netty4/Netty4HttpRequest.java

@@ -162,7 +162,7 @@ public class Netty4HttpRequest implements HttpRequest {
         String cookieString = request.headers().get(HttpHeaderNames.COOKIE);
         if (cookieString != null) {
             Set<Cookie> cookies = ServerCookieDecoder.STRICT.decode(cookieString);
-            if (!cookies.isEmpty()) {
+            if (cookies.isEmpty() == false) {
                 return ServerCookieEncoder.STRICT.encode(cookies);
             }
         }

modules/transport-netty4/src/main/java/org/elasticsearch/transport/netty4/Netty4Utils.java

@@ -49,7 +49,7 @@ public class Netty4Utils {
     public static void setAvailableProcessors(final int availableProcessors) {
         // we set this to false in tests to avoid tests that randomly set processors from stepping on each other
         final boolean set = Booleans.parseBoolean(System.getProperty("es.set.netty.runtime.available.processors", "true"));
-        if (!set) {
+        if (set == false) {
             return;
         }
 

modules/transport-netty4/src/test/java/org/elasticsearch/http/netty4/Netty4HttpPipeliningHandlerTests.java

@@ -75,11 +75,11 @@ public class Netty4HttpPipeliningHandlerTests extends ESTestCase {
     }
 
     private void shutdownExecutorService() throws InterruptedException {
-        if (!handlerService.isShutdown()) {
+        if (handlerService.isShutdown() == false) {
             handlerService.shutdown();
             handlerService.awaitTermination(10, TimeUnit.SECONDS);
         }
-        if (!eventLoopService.isShutdown()) {
+        if (eventLoopService.isShutdown() == false) {
             eventLoopService.shutdown();
             eventLoopService.awaitTermination(10, TimeUnit.SECONDS);
         }

plugins/analysis-icu/src/main/java/org/elasticsearch/index/analysis/IcuAnalyzerProvider.java

@@ -39,7 +39,7 @@ public class IcuAnalyzerProvider extends AbstractIndexAnalyzerProvider<Analyzer>
         super(indexSettings, name, settings);
         String method = settings.get("method", "nfkc_cf");
         String mode = settings.get("mode", "compose");
-        if (!"compose".equals(mode) && !"decompose".equals(mode)) {
+        if ("compose".equals(mode) == false && "decompose".equals(mode) == false) {
             throw new IllegalArgumentException("Unknown mode [" + mode + "] in analyzer [" + name +
                 "], expected one of [compose, decompose]");
         }

plugins/analysis-icu/src/main/java/org/elasticsearch/index/analysis/IcuNormalizerCharFilterFactory.java

@@ -44,7 +44,7 @@ public class IcuNormalizerCharFilterFactory extends AbstractCharFilterFactory im
         super(indexSettings, name);
         String method = settings.get("name", "nfkc_cf");
         String mode = settings.get("mode");
-        if (!"compose".equals(mode) && !"decompose".equals(mode)) {
+        if ("compose".equals(mode) == false && "decompose".equals(mode) == false) {
             mode = "compose";
         }
         Normalizer2 normalizer = Normalizer2.getInstance(

plugins/analysis-phonetic/src/main/java/org/elasticsearch/index/analysis/phonetic/KoelnerPhonetik.java

@@ -19,6 +19,9 @@
 
 package org.elasticsearch.index.analysis.phonetic;
 
+import org.apache.commons.codec.EncoderException;
+import org.apache.commons.codec.StringEncoder;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
@@ -28,9 +31,6 @@ import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-import org.apache.commons.codec.EncoderException;
-import org.apache.commons.codec.StringEncoder;
-
 /**
  * Kölner Phonetik
  *
@@ -141,14 +141,14 @@ public class KoelnerPhonetik implements StringEncoder {
         String primaryForm = str;
         List<String> parts = new ArrayList<>();
         parts.add(primaryForm.replaceAll("[^\\p{L}\\p{N}]", ""));
-        if (!primary) {
+        if (primary == false) {
             List<String> tmpParts = new ArrayList<>(Arrays.asList(str.split("[\\p{Z}\\p{C}\\p{P}]")));
             int numberOfParts = tmpParts.size();
             while (tmpParts.size() > 0) {
                 StringBuilder part = new StringBuilder();
                 for (int i = 0; i < tmpParts.size(); i++) {
                     part.append(tmpParts.get(i));
-                    if (!(i + 1 == numberOfParts)) {
+                    if ((i + 1 == numberOfParts) == false) {
                         parts.add(part.toString());
                     }
                 }

plugins/discovery-azure-classic/src/main/java/org/elasticsearch/discovery/azure/classic/AzureSeedHostsProvider.java

@@ -182,7 +182,7 @@ public class AzureSeedHostsProvider implements SeedHostsProvider {
             }
 
             // If provided, we check the deployment name
-            if (Strings.hasLength(deploymentName) && !deploymentName.equals(deployment.getName())) {
+            if (Strings.hasLength(deploymentName) && deploymentName.equals(deployment.getName()) == false) {
                 logger.debug("current deployment name [{}] different from [{}]. skipping...",
                         deployment.getName(), deploymentName);
                 continue;

plugins/discovery-ec2/src/main/java/org/elasticsearch/discovery/ec2/AwsEc2SeedHostsProvider.java

@@ -121,7 +121,7 @@ class AwsEc2SeedHostsProvider implements SeedHostsProvider {
         for (final Reservation reservation : descInstances.getReservations()) {
             for (final Instance instance : reservation.getInstances()) {
                 // lets see if we can filter based on groups
-                if (!groups.isEmpty()) {
+                if (groups.isEmpty() == false) {
                     final List<GroupIdentifier> instanceSecurityGroups = instance.getSecurityGroups();
                     final List<String> securityGroupNames = new ArrayList<>(instanceSecurityGroups.size());
                     final List<String> securityGroupIds = new ArrayList<>(instanceSecurityGroups.size());
@@ -140,7 +140,7 @@ class AwsEc2SeedHostsProvider implements SeedHostsProvider {
                         }
                     } else {
                         // We need tp match all group names or group ids, otherwise we ignore this instance
-                        if (!(securityGroupNames.containsAll(groups) || securityGroupIds.containsAll(groups))) {
+                        if ((securityGroupNames.containsAll(groups) || securityGroupIds.containsAll(groups)) == false) {
                             logger.trace("filtering out instance {} based on groups {}, does not include all of {}",
                                     instance.getInstanceId(), instanceSecurityGroups, groups);
                             // continue to the next instance
@@ -209,7 +209,7 @@ class AwsEc2SeedHostsProvider implements SeedHostsProvider {
             );
         }
 
-        if (!availabilityZones.isEmpty()) {
+        if (availabilityZones.isEmpty() == false) {
             // OR relationship amongst multiple values of the availability-zone filter
             describeInstancesRequest.withFilters(
                 new Filter("availability-zone").withValues(availabilityZones)

plugins/discovery-gce/src/main/java/org/elasticsearch/discovery/gce/GceSeedHostsProvider.java

@@ -171,7 +171,7 @@ public class GceSeedHostsProvider implements SeedHostsProvider {
                                     break;
                                 }
                             }
-                            if (!found) {
+                            if (found == false) {
                                 filterByTag = true;
                                 break;
                             }

plugins/repository-azure/src/main/java/org/elasticsearch/repositories/azure/AzureBlobContainer.java

@@ -58,7 +58,7 @@ public class AzureBlobContainer extends AbstractBlobContainer {
 
     private InputStream openInputStream(String blobName, long position, @Nullable Long length) throws IOException {
         logger.trace("readBlob({}) from position [{}] with length [{}]", blobName, position, length != null ? length : "unlimited");
-        if (blobStore.getLocationMode() == LocationMode.SECONDARY_ONLY && !blobExists(blobName)) {
+        if (blobStore.getLocationMode() == LocationMode.SECONDARY_ONLY && blobExists(blobName) == false) {
             // On Azure, if the location path is a secondary location, and the blob does not
             // exist, instead of returning immediately from the getInputStream call below
             // with a 404 StorageException, Azure keeps trying and trying for a long timeout

plugins/repository-gcs/src/main/java/org/elasticsearch/repositories/gcs/GoogleCloudStorageHttpStatsCollector.java

@@ -64,7 +64,7 @@ final class GoogleCloudStorageHttpStatsCollector implements HttpResponseIntercep
     @Override
     public void interceptResponse(final HttpResponse response) {
         // TODO keep track of unsuccessful requests in different entries
-        if (!response.isSuccessStatusCode())
+        if (response.isSuccessStatusCode() == false)
             return;
 
         final HttpRequest request = response.getRequest();

plugins/repository-hdfs/src/main/java/org/elasticsearch/repositories/hdfs/HdfsBlobStore.java

@@ -50,7 +50,7 @@ final class HdfsBlobStore implements BlobStore {
         this.bufferSize = bufferSize;
         this.root = execute(fileContext1 -> fileContext1.makeQualified(new Path(path)));
         this.readOnly = readOnly;
-        if (!readOnly) {
+        if (readOnly == false) {
             try {
                 mkdirs(root);
             } catch (FileAlreadyExistsException ok) {
@@ -78,7 +78,7 @@ final class HdfsBlobStore implements BlobStore {
 
     private Path buildHdfsPath(BlobPath blobPath) {
         final Path path = translateToHdfsPath(blobPath);
-        if (!readOnly) {
+        if (readOnly == false) {
             try {
                 mkdirs(path);
             } catch (FileAlreadyExistsException ok) {

plugins/transport-nio/src/main/java/org/elasticsearch/http/nio/NioHttpRequest.java

@@ -161,7 +161,7 @@ public class NioHttpRequest implements HttpRequest {
         String cookieString = request.headers().get(HttpHeaderNames.COOKIE);
         if (cookieString != null) {
             Set<Cookie> cookies = ServerCookieDecoder.STRICT.decode(cookieString);
-            if (!cookies.isEmpty()) {
+            if (cookies.isEmpty() == false) {
                 return ServerCookieEncoder.STRICT.encode(cookies);
             }
         }

plugins/transport-nio/src/test/java/org/elasticsearch/http/nio/NioHttpPipeliningHandlerTests.java

@@ -75,11 +75,11 @@ public class NioHttpPipeliningHandlerTests extends ESTestCase {
     }
 
     private void shutdownExecutorService() throws InterruptedException {
-        if (!handlerService.isShutdown()) {
+        if (handlerService.isShutdown() == false) {
             handlerService.shutdown();
             handlerService.awaitTermination(10, TimeUnit.SECONDS);
         }
-        if (!eventLoopService.isShutdown()) {
+        if (eventLoopService.isShutdown() == false) {
             eventLoopService.shutdown();
             eventLoopService.awaitTermination(10, TimeUnit.SECONDS);
         }

qa/evil-tests/src/test/java/org/elasticsearch/bootstrap/SystemCallFilterTests.java

@@ -37,7 +37,7 @@ public class SystemCallFilterTests extends ESTestCase {
         // otherwise, since we don't have TSYNC support, rules are not applied to the test thread
         // (randomizedrunner class initialization happens in its own thread, after the test thread is created)
         // instead we just forcefully run it for the test thread here.
-        if (!JNANatives.LOCAL_SYSTEM_CALL_FILTER_ALL) {
+        if (JNANatives.LOCAL_SYSTEM_CALL_FILTER_ALL == false) {
             try {
                 SystemCallFilter.init(createTempDir());
             } catch (Exception e) {

test/external-modules/delayed-aggs/src/main/java/org/elasticsearch/search/aggregations/DelayedShardAggregationBuilder.java

@@ -126,7 +126,7 @@ public class DelayedShardAggregationBuilder extends AbstractAggregationBuilder<D
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
-        if (!super.equals(o)) return false;
+        if (super.equals(o) == false) return false;
         DelayedShardAggregationBuilder that = (DelayedShardAggregationBuilder) o;
         return Objects.equals(delay, that.delay);
     }

test/framework/src/main/java/org/elasticsearch/common/util/MockBigArrays.java

@@ -101,7 +101,7 @@ public class MockBigArrays extends BigArrays {
 
     public static void ensureAllArraysAreReleased() throws Exception {
         final Map<Object, Object> masterCopy = new HashMap<>(ACQUIRED_ARRAYS);
-        if (!masterCopy.isEmpty()) {
+        if (masterCopy.isEmpty() == false) {
             // not empty, we might be executing on a shared cluster that keeps on obtaining
             // and releasing arrays, lets make sure that after a reasonable timeout, all master
             // copy (snapshot) have been released
@@ -110,7 +110,7 @@ public class MockBigArrays extends BigArrays {
             } catch (AssertionError ex) {
                 masterCopy.keySet().retainAll(ACQUIRED_ARRAYS.keySet());
                 ACQUIRED_ARRAYS.keySet().removeAll(masterCopy.keySet()); // remove all existing master copy we will report on
-                if (!masterCopy.isEmpty()) {
+                if (masterCopy.isEmpty() == false) {
                     Iterator<Object> causes = masterCopy.values().iterator();
                     Object firstCause = causes.next();
                     RuntimeException exception = new RuntimeException(masterCopy.size() + " arrays have not been released",
@@ -170,7 +170,7 @@ public class MockBigArrays extends BigArrays {
     @Override
     public ByteArray newByteArray(long size, boolean clearOnResize) {
         final ByteArrayWrapper array = new ByteArrayWrapper(super.newByteArray(size, clearOnResize), clearOnResize);
-        if (!clearOnResize) {
+        if (clearOnResize == false) {
             array.randomizeContent(0, size);
         }
         return array;
@@ -187,7 +187,7 @@ public class MockBigArrays extends BigArrays {
         } else {
             arr = new ByteArrayWrapper(array, arr.clearOnResize);
         }
-        if (!arr.clearOnResize) {
+        if (arr.clearOnResize == false) {
             arr.randomizeContent(originalSize, size);
         }
         return arr;
@@ -196,7 +196,7 @@ public class MockBigArrays extends BigArrays {
     @Override
     public IntArray newIntArray(long size, boolean clearOnResize) {
         final IntArrayWrapper array = new IntArrayWrapper(super.newIntArray(size, clearOnResize), clearOnResize);
-        if (!clearOnResize) {
+        if (clearOnResize == false) {
             array.randomizeContent(0, size);
         }
         return array;
@@ -213,7 +213,7 @@ public class MockBigArrays extends BigArrays {
         } else {
             arr = new IntArrayWrapper(array, arr.clearOnResize);
         }
-        if (!arr.clearOnResize) {
+        if (arr.clearOnResize == false) {
             arr.randomizeContent(originalSize, size);
         }
         return arr;
@@ -222,7 +222,7 @@ public class MockBigArrays extends BigArrays {
     @Override
     public LongArray newLongArray(long size, boolean clearOnResize) {
         final LongArrayWrapper array = new LongArrayWrapper(super.newLongArray(size, clearOnResize), clearOnResize);
-        if (!clearOnResize) {
+        if (clearOnResize == false) {
             array.randomizeContent(0, size);
         }
         return array;
@@ -239,7 +239,7 @@ public class MockBigArrays extends BigArrays {
         } else {
             arr = new LongArrayWrapper(array, arr.clearOnResize);
         }
-        if (!arr.clearOnResize) {
+        if (arr.clearOnResize == false) {
             arr.randomizeContent(originalSize, size);
         }
         return arr;
@@ -248,7 +248,7 @@ public class MockBigArrays extends BigArrays {
     @Override
     public FloatArray newFloatArray(long size, boolean clearOnResize) {
         final FloatArrayWrapper array = new FloatArrayWrapper(super.newFloatArray(size, clearOnResize), clearOnResize);
-        if (!clearOnResize) {
+        if (clearOnResize == false) {
             array.randomizeContent(0, size);
         }
         return array;
@@ -265,7 +265,7 @@ public class MockBigArrays extends BigArrays {
         } else {
             arr = new FloatArrayWrapper(array, arr.clearOnResize);
         }
-        if (!arr.clearOnResize) {
+        if (arr.clearOnResize == false) {
             arr.randomizeContent(originalSize, size);
         }
         return arr;
@@ -274,7 +274,7 @@ public class MockBigArrays extends BigArrays {
     @Override
     public DoubleArray newDoubleArray(long size, boolean clearOnResize) {
         final DoubleArrayWrapper array = new DoubleArrayWrapper(super.newDoubleArray(size, clearOnResize), clearOnResize);
-        if (!clearOnResize) {
+        if (clearOnResize == false) {
             array.randomizeContent(0, size);
         }
         return array;
@@ -291,7 +291,7 @@ public class MockBigArrays extends BigArrays {
         } else {
             arr = new DoubleArrayWrapper(array, arr.clearOnResize);
         }
-        if (!arr.clearOnResize) {
+        if (arr.clearOnResize == false) {
             arr.randomizeContent(originalSize, size);
         }
         return arr;

test/framework/src/main/java/org/elasticsearch/common/util/MockPageCacheRecycler.java

@@ -41,16 +41,16 @@ public class MockPageCacheRecycler extends PageCacheRecycler {
 
     public static void ensureAllPagesAreReleased() throws Exception {
         final Map<Object, Throwable> masterCopy = new HashMap<>(ACQUIRED_PAGES);
-        if (!masterCopy.isEmpty()) {
+        if (masterCopy.isEmpty() == false) {
             // not empty, we might be executing on a shared cluster that keeps on obtaining
             // and releasing pages, lets make sure that after a reasonable timeout, all master
             // copy (snapshot) have been released
             final boolean success =
                 waitUntil(() -> Sets.haveEmptyIntersection(masterCopy.keySet(), ACQUIRED_PAGES.keySet()));
-            if (!success) {
+            if (success == false) {
                 masterCopy.keySet().retainAll(ACQUIRED_PAGES.keySet());
                 ACQUIRED_PAGES.keySet().removeAll(masterCopy.keySet()); // remove all existing master copy we will report on
-                if (!masterCopy.isEmpty()) {
+                if (masterCopy.isEmpty() == false) {
                     Iterator<Throwable> causes = masterCopy.values().iterator();
                     Throwable firstCause = causes.next();
                     RuntimeException exception = new RuntimeException(masterCopy.size() + " pages have not been released", firstCause);
@@ -120,7 +120,7 @@ public class MockPageCacheRecycler extends PageCacheRecycler {
     @Override
     public V<byte[]> bytePage(boolean clear) {
         final V<byte[]> page = super.bytePage(clear);
-        if (!clear) {
+        if (clear == false) {
             Arrays.fill(page.v(), 0, page.v().length, (byte)random.nextInt(1<<8));
         }
         return wrap(page);
@@ -129,7 +129,7 @@ public class MockPageCacheRecycler extends PageCacheRecycler {
     @Override
     public V<int[]> intPage(boolean clear) {
         final V<int[]> page = super.intPage(clear);
-        if (!clear) {
+        if (clear == false) {
             Arrays.fill(page.v(), 0, page.v().length, random.nextInt());
         }
         return wrap(page);
@@ -138,7 +138,7 @@ public class MockPageCacheRecycler extends PageCacheRecycler {
     @Override
     public V<long[]> longPage(boolean clear) {
         final V<long[]> page = super.longPage(clear);
-        if (!clear) {
+        if (clear == false) {
             Arrays.fill(page.v(), 0, page.v().length, random.nextLong());
         }
         return wrap(page);

test/framework/src/main/java/org/elasticsearch/test/BackgroundIndexer.java

@@ -134,13 +134,13 @@ public class BackgroundIndexer implements AutoCloseable {
                     try {
                         startLatch.await();
                         logger.info("**** starting indexing thread {}", indexerId);
-                        while (!stop.get()) {
+                        while (stop.get() == false) {
                             if (batch) {
                                 int batchSize = threadRandom.nextInt(20) + 1;
                                 if (hasBudget.get()) {
                                     // always try to get at least one
                                     batchSize = Math.max(Math.min(batchSize, availableBudget.availablePermits()), 1);
-                                    if (!availableBudget.tryAcquire(batchSize, 250, TimeUnit.MILLISECONDS)) {
+                                    if (availableBudget.tryAcquire(batchSize, 250, TimeUnit.MILLISECONDS) == false) {
                                         // time out -> check if we have to stop.
                                         continue;
                                     }
@@ -173,7 +173,7 @@ public class BackgroundIndexer implements AutoCloseable {
                                 }
                             } else {
 
-                                if (hasBudget.get() && !availableBudget.tryAcquire(250, TimeUnit.MILLISECONDS)) {
+                                if (hasBudget.get() && availableBudget.tryAcquire(250, TimeUnit.MILLISECONDS) == false) {
                                     // time out -> check if we have to stop.
                                     continue;
                                 }
@@ -278,7 +278,7 @@ public class BackgroundIndexer implements AutoCloseable {
      * @param numOfDocs number of document to index before pausing. Set to -1 to have no limit.
      */
     public void start(int numOfDocs) {
-        assert !stop.get() : "background indexer can not be started after it has stopped";
+        assert stop.get() == false : "background indexer can not be started after it has stopped";
         setBudget(numOfDocs);
         startLatch.countDown();
     }

test/framework/src/main/java/org/elasticsearch/test/ESIntegTestCase.java

@@ -517,7 +517,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
     }
 
     private static void clearClusters() throws Exception {
-        if (!clusters.isEmpty()) {
+        if (clusters.isEmpty() == false) {
             IOUtils.close(clusters.values());
             clusters.clear();
         }
@@ -568,7 +568,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
             }
             success = true;
         } finally {
-            if (!success) {
+            if (success == false) {
                 // if we failed here that means that something broke horribly so we should clear all clusters
                 // TODO: just let the exception happen, WTF is all this horseshit
                 // afterTestRule.forceFailure();
@@ -596,7 +596,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
     }
 
     public static InternalTestCluster internalCluster() {
-        if (!isInternalCluster()) {
+        if (isInternalCluster() == false) {
             throw new UnsupportedOperationException("current test cluster is immutable");
         }
         return (InternalTestCluster) currentCluster;
@@ -727,7 +727,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
                 created.add(name);
                 success = true;
             } finally {
-                if (!success && !created.isEmpty()) {
+                if (success == false && created.isEmpty() == false) {
                     cluster().wipeIndices(created.toArray(new String[created.size()]));
                 }
             }
@@ -841,7 +841,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
             getExcludeSettings(n, builder);
         }
         Settings build = builder.build();
-        if (!build.isEmpty()) {
+        if (build.isEmpty() == false) {
             logger.debug("allowNodes: updating [{}]'s setting to [{}]", index, build.toDelimitedString(';'));
             client().admin().indices().prepareUpdateSettings(index).setSettings(build).execute().actionGet();
         }
@@ -1427,7 +1427,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
             indices.add(builder.request().index());
         }
         Set<List<String>> bogusIds = new HashSet<>(); // (index, type, id)
-        if (random.nextBoolean() && !builders.isEmpty() && dummyDocuments) {
+        if (random.nextBoolean() && builders.isEmpty() == false && dummyDocuments) {
             builders = new ArrayList<>(builders);
             // inject some bogus docs
             final int numBogusDocs = scaledRandomIntBetween(1, builders.size() * 2);
@@ -1489,7 +1489,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
             }
         }
         assertThat(actualErrors, emptyIterable());
-        if (!bogusIds.isEmpty()) {
+        if (bogusIds.isEmpty() == false) {
             // delete the bogus types again - it might trigger merges or at least holes in the segments and enforces deleted docs!
             for (List<String> doc : bogusIds) {
                 assertEquals("failed to delete a dummy doc [" + doc.get(0) + "][" + doc.get(1) + "]",
@@ -2121,7 +2121,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
                 INSTANCE.setupSuiteScopeCluster();
                 success = true;
             } finally {
-                if (!success) {
+                if (success == false) {
                     afterClass();
                 }
             }

test/framework/src/main/java/org/elasticsearch/test/InternalTestCluster.java

@@ -540,7 +540,7 @@ public final class InternalTestCluster extends TestCluster {
     }
 
     private void ensureOpen() {
-        if (!open.get()) {
+        if (open.get() == false) {
             throw new RuntimeException("Cluster is already closed");
         }
     }
@@ -623,7 +623,7 @@ public final class InternalTestCluster extends TestCluster {
         }
 
         stopNodesAndClients(nodesToRemove);
-        if (!nodesToRemove.isEmpty() && size() > 0) {
+        if (nodesToRemove.isEmpty() == false && size() > 0) {
             validateClusterFormed();
         }
     }
@@ -1394,7 +1394,7 @@ public final class InternalTestCluster extends TestCluster {
     }
 
     public synchronized void wipePendingDataDirectories() {
-        if (!dataDirToClean.isEmpty()) {
+        if (dataDirToClean.isEmpty() == false) {
             try {
                 for (Path path : dataDirToClean) {
                     try {
@@ -2063,7 +2063,7 @@ public final class InternalTestCluster extends TestCluster {
     }
 
     private synchronized void publishNode(NodeAndClient nodeAndClient) {
-        assert !nodeAndClient.node().isClosed();
+        assert nodeAndClient.node().isClosed() == false;
         final NavigableMap<String, NodeAndClient> newNodes = new TreeMap<>(nodes);
         newNodes.put(nodeAndClient.name, nodeAndClient);
         nodes = Collections.unmodifiableNavigableMap(newNodes);

test/framework/src/main/java/org/elasticsearch/test/TestCluster.java

@@ -148,7 +148,7 @@ public abstract class TestCluster implements Closeable {
                     for (IndexMetadata indexMetadata : clusterStateResponse.getState().metadata()) {
                         concreteIndices.add(indexMetadata.getIndex().getName());
                     }
-                    if (!concreteIndices.isEmpty()) {
+                    if (concreteIndices.isEmpty() == false) {
                         assertAcked(client().admin().indices().prepareDelete(concreteIndices.toArray(String.class)));
                     }
                 }

test/framework/src/main/java/org/elasticsearch/test/TestCustomMetadata.java

@@ -45,11 +45,15 @@ public abstract class TestCustomMetadata extends AbstractNamedDiffable<Metadata.
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
-        if (o == null || getClass() != o.getClass()) return false;
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
 
         TestCustomMetadata that = (TestCustomMetadata) o;
 
-        if (!data.equals(that.data)) return false;
+        if (data.equals(that.data) == false) {
+            return false;
+        }
 
         return true;
     }