diff --git a/benchmarks/build.gradle b/benchmarks/build.gradle
index bd80deda89c6f..e7ee5a059ab37 100644
--- a/benchmarks/build.gradle
+++ b/benchmarks/build.gradle
@@ -30,7 +30,7 @@ buildscript {
 
 apply plugin: 'elasticsearch.build'
 
-// order of this seciont matters, see: https://github.com/johnrengelman/shadow/issues/336
+// order of this section matters, see: https://github.com/johnrengelman/shadow/issues/336
 apply plugin: 'application' // have the shadow plugin provide the runShadow task
 mainClassName = 'org.openjdk.jmh.Main'
 apply plugin: 'com.github.johnrengelman.shadow' // build an uberjar with all benchmarks
diff --git a/build.gradle b/build.gradle
index 9bb08cf29dbbc..862943b50f5eb 100644
--- a/build.gradle
+++ b/build.gradle
@@ -326,6 +326,9 @@ gradle.projectsEvaluated {
       // :test:framework:test cannot run before and after :server:test
       return
     }
+    if (tasks.findByPath('test') != null && tasks.findByPath('integTest') != null) {
+      integTest.mustRunAfter test
+    }
     configurations.all { Configuration configuration ->
       /*
        * The featureAwarePlugin configuration has a dependency on x-pack:plugin:core and x-pack:plugin:core has a dependency on the
@@ -575,3 +578,28 @@ gradle.projectsEvaluated {
     }
   }
 }
+
+if (System.properties.get("build.compare") != null) {
+  apply plugin: 'compare-gradle-builds'
+  compareGradleBuilds {
+    ext.referenceProject = System.properties.get("build.compare")
+    doFirst {
+      if (file(referenceProject).exists() == false) {
+        throw new GradleException(
+                "Use git worktree to check out a version to compare against to ../elasticsearch_build_reference"
+        )
+      }
+    }
+    sourceBuild {
+      gradleVersion = "4.7" // does not default to gradle weapper of project dir, but current version
+      projectDir = referenceProject
+      tasks = ["clean", "assemble"]
+      arguments = ["-Dbuild.compare_friendly=true"]
+    }
+    targetBuild {
+      tasks = ["clean", "assemble"]
+      // use -Dorg.gradle.java.home= to alter jdk versions
+      arguments = ["-Dbuild.compare_friendly=true"]
+    }
+  }
+}
diff --git a/buildSrc/build.gradle b/buildSrc/build.gradle
index 5256968b6ca3e..9c139eee2152a 100644
--- a/buildSrc/build.gradle
+++ b/buildSrc/build.gradle
@@ -106,7 +106,6 @@ GradleVersion logVersion = GradleVersion.current() > GradleVersion.version('4.3'
 
 dependencies {
   compileOnly "org.gradle:gradle-logging:${logVersion.getVersion()}"
-  compile 'ru.vyarus:gradle-animalsniffer-plugin:1.2.0' // Gradle 2.14 requires a version > 1.0.1
 }
 
 /*****************************************************************************
diff --git a/buildSrc/src/main/groovy/com/carrotsearch/gradle/junit4/RandomizedTestingPlugin.groovy b/buildSrc/src/main/groovy/com/carrotsearch/gradle/junit4/RandomizedTestingPlugin.groovy
index c375f773bf9b5..809aa4fb57ea4 100644
--- a/buildSrc/src/main/groovy/com/carrotsearch/gradle/junit4/RandomizedTestingPlugin.groovy
+++ b/buildSrc/src/main/groovy/com/carrotsearch/gradle/junit4/RandomizedTestingPlugin.groovy
@@ -1,20 +1,44 @@
 package com.carrotsearch.gradle.junit4
 
 import com.carrotsearch.ant.tasks.junit4.JUnit4
-import org.gradle.api.AntBuilder
+import org.gradle.api.GradleException
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.Task
+import org.gradle.api.UnknownTaskException
 import org.gradle.api.plugins.JavaBasePlugin
 import org.gradle.api.tasks.TaskContainer
+import org.gradle.api.tasks.TaskProvider
 import org.gradle.api.tasks.testing.Test
 
+import java.util.concurrent.atomic.AtomicBoolean
+
 class RandomizedTestingPlugin implements Plugin<Project> {
 
+    static private AtomicBoolean sanityCheckConfigured = new AtomicBoolean(false)
+
     void apply(Project project) {
         setupSeed(project)
         replaceTestTask(project.tasks)
         configureAnt(project.ant)
+        configureSanityCheck(project)
+    }
+
+    private static void configureSanityCheck(Project project) {
+        // Check the task graph to confirm tasks were indeed replaced
+        // https://github.com/elastic/elasticsearch/issues/31324
+        if (sanityCheckConfigured.getAndSet(true) == false) {
+            project.rootProject.getGradle().getTaskGraph().whenReady {
+                List<Task> nonConforming = project.getGradle().getTaskGraph().allTasks
+                        .findAll { it.name == "test" }
+                        .findAll { (it instanceof RandomizedTestingTask) == false}
+                        .collect { "${it.path} -> ${it.class}" }
+                if (nonConforming.isEmpty() == false) {
+                    throw new GradleException("Found the ${nonConforming.size()} `test` tasks:" +
+                            "\n  ${nonConforming.join("\n  ")}")
+                }
+            }
+        }
     }
 
     /**
@@ -45,29 +69,32 @@ class RandomizedTestingPlugin implements Plugin<Project> {
     }
 
     static void replaceTestTask(TaskContainer tasks) {
-        Test oldTestTask = tasks.findByPath('test')
-        if (oldTestTask == null) {
+        // Gradle 4.8 introduced lazy tasks, thus we deal both with the `test` task as well as it's provider
+        // https://github.com/gradle/gradle/issues/5730#issuecomment-398822153
+        // since we can't be sure if the task was ever realized, we remove both the provider and the task
+        TaskProvider<Test> oldTestProvider
+        try {
+            oldTestProvider = tasks.getByNameLater(Test, 'test')
+        } catch (UnknownTaskException unused) {
             // no test task, ok, user will use testing task on their own
             return
         }
-        tasks.remove(oldTestTask)
+        Test oldTestTask = oldTestProvider.get()
 
-        Map properties = [
-            name: 'test',
-            type: RandomizedTestingTask,
-            dependsOn: oldTestTask.dependsOn,
-            group: JavaBasePlugin.VERIFICATION_GROUP,
-            description: 'Runs unit tests with the randomized testing framework'
-        ]
-        RandomizedTestingTask newTestTask = tasks.create(properties)
-        newTestTask.classpath = oldTestTask.classpath
-        newTestTask.testClassesDir = oldTestTask.project.sourceSets.test.output.classesDir
-        // since gradle 4.5, tasks immutable dependencies are "hidden" (do not show up in dependsOn)
-        // so we must explicitly add a dependency on generating the test classpath
-        newTestTask.dependsOn('testClasses')
+        // we still have to use replace here despite the remove above because the task container knows about the provider
+        // by the same name
+        RandomizedTestingTask newTestTask = tasks.replace('test', RandomizedTestingTask)
+        newTestTask.configure{
+            group =  JavaBasePlugin.VERIFICATION_GROUP
+            description = 'Runs unit tests with the randomized testing framework'
+            dependsOn oldTestTask.dependsOn, 'testClasses'
+            classpath = oldTestTask.classpath
+            testClassesDir = oldTestTask.project.sourceSets.test.output.classesDir
+        }
 
         // hack so check task depends on custom test
-        Task checkTask = tasks.findByPath('check')
+        Task checkTask = tasks.getByName('check')
+        checkTask.dependsOn.remove(oldTestProvider)
         checkTask.dependsOn.remove(oldTestTask)
         checkTask.dependsOn.add(newTestTask)
     }
diff --git a/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy b/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
index eb3cd1dc8c6da..3363c8534a40e 100644
--- a/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
+++ b/buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy
@@ -348,7 +348,9 @@ class BuildPlugin implements Plugin<Project> {
                 // just a self contained test-fixture configuration, likely transitive and hellacious
                 return
             }
-            configuration.resolutionStrategy.failOnVersionConflict()
+            configuration.resolutionStrategy { 
+                failOnVersionConflict()
+            }
         })
 
         // force all dependencies added directly to compile/testCompile to be non-transitive, except for ES itself
@@ -475,13 +477,17 @@ class BuildPlugin implements Plugin<Project> {
                 }
             }
 
-            project.tasks.withType(GenerateMavenPom.class) { GenerateMavenPom t ->
-                // place the pom next to the jar it is for
-                t.destination = new File(project.buildDir, "distributions/${project.archivesBaseName}-${project.version}.pom")
-                // build poms with assemble (if the assemble task exists)
-                Task assemble = project.tasks.findByName('assemble')
-                if (assemble) {
-                    assemble.dependsOn(t)
+            // Work around Gradle 4.8 issue until we `enableFeaturePreview('STABLE_PUBLISHING')`
+            // https://github.com/gradle/gradle/issues/5696#issuecomment-396965185
+            project.getGradle().getTaskGraph().whenReady {
+                project.tasks.withType(GenerateMavenPom.class) { GenerateMavenPom t ->
+                    // place the pom next to the jar it is for
+                    t.destination = new File(project.buildDir, "distributions/${project.archivesBaseName}-${project.version}.pom")
+                    // build poms with assemble (if the assemble task exists)
+                    Task assemble = project.tasks.findByName('assemble')
+                    if (assemble) {
+                        assemble.dependsOn(t)
+                    }
                 }
             }
         }
@@ -625,6 +631,10 @@ class BuildPlugin implements Plugin<Project> {
                         jarTask.manifest.attributes('Change': shortHash)
                     }
                 }
+                // Force manifest entries that change by nature to a constant to be able to compare builds more effectively
+                if (System.properties.getProperty("build.compare_friendly", "false") == "true") {
+                    jarTask.manifest.getAttributes().clear()
+                }
             }
             // add license/notice files
             project.afterEvaluate {
diff --git a/client/rest/src/main/java/org/elasticsearch/client/RestClient.java b/client/rest/src/main/java/org/elasticsearch/client/RestClient.java
index 77c11db455e47..d07e9e3c1cab7 100644
--- a/client/rest/src/main/java/org/elasticsearch/client/RestClient.java
+++ b/client/rest/src/main/java/org/elasticsearch/client/RestClient.java
@@ -1010,8 +1010,8 @@ public int compareTo(DeadNode rhs) {
     }
 
     /**
-     * Adapts an <code>Iterator<DeadNodeAndRevival></code> into an
-     * <code>Iterator<Node></code>.
+     * Adapts an <code>Iterator&lt;DeadNodeAndRevival&gt;</code> into an
+     * <code>Iterator&lt;Node&gt;</code>.
      */
     private static class DeadNodeIteratorAdapter implements Iterator<Node> {
         private final Iterator<DeadNode> itr;
diff --git a/client/rest/src/test/java/org/elasticsearch/client/RestClientSingleHostTests.java b/client/rest/src/test/java/org/elasticsearch/client/RestClientSingleHostTests.java
index 6b7725666d42d..cb326f4a24c8d 100644
--- a/client/rest/src/test/java/org/elasticsearch/client/RestClientSingleHostTests.java
+++ b/client/rest/src/test/java/org/elasticsearch/client/RestClientSingleHostTests.java
@@ -314,7 +314,7 @@ public void testBody() throws IOException {
     }
 
     /**
-     * @deprecated will remove method in 7.0 but needs tests until then. Replaced by {@link RequestTests#testAddHeaders()}.
+     * @deprecated will remove method in 7.0 but needs tests until then. Replaced by {@link RequestTests}.
      */
     @Deprecated
     public void tesPerformRequestOldStyleNullHeaders() throws IOException {
diff --git a/client/rest/src/test/java/org/elasticsearch/client/RestClientTests.java b/client/rest/src/test/java/org/elasticsearch/client/RestClientTests.java
index 030c2fca6272a..30289ec84c9df 100644
--- a/client/rest/src/test/java/org/elasticsearch/client/RestClientTests.java
+++ b/client/rest/src/test/java/org/elasticsearch/client/RestClientTests.java
@@ -141,7 +141,7 @@ public void onFailure(Exception exception) {
     }
 
     /**
-     * @deprecated will remove method in 7.0 but needs tests until then. Replaced by {@link RequestTests#testAddHeader()}.
+     * @deprecated will remove method in 7.0 but needs tests until then. Replaced by {@link RequestTests}.
      */
     @Deprecated
     public void testPerformOldStyleAsyncWithNullHeaders() throws Exception {
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index a5fe1cb94b9ee..758de960ec794 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 7962563f742fe..37e3d3699fafc 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.7-all.zip
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.8.1-all.zip
 zipStoreBase=GRADLE_USER_HOME
-distributionSha256Sum=203f4537da8b8075e38c036a6d14cb71b1149de5bf0a8f6db32ac2833a1d1294
+zipStorePath=wrapper/dists
+distributionSha256Sum=ce1645ff129d11aad62dab70d63426fdce6cfd646fa309dc5dc5255dd03c7c11
diff --git a/server/src/main/java/org/elasticsearch/search/SearchHit.java b/server/src/main/java/org/elasticsearch/search/SearchHit.java
index 34b48fce941f8..8c688cbf4466a 100644
--- a/server/src/main/java/org/elasticsearch/search/SearchHit.java
+++ b/server/src/main/java/org/elasticsearch/search/SearchHit.java
@@ -497,8 +497,8 @@ public XContentBuilder toInnerXContent(XContentBuilder builder, Params params) t
      * This parser outputs a temporary map of the objects needed to create the
      * SearchHit instead of directly creating the SearchHit. The reason for this
      * is that this way we can reuse the parser when parsing xContent from
-     * {@link CompletionSuggestion.Entry.Option} which unfortunately inlines the
-     * output of
+     * {@link org.elasticsearch.search.suggest.completion.CompletionSuggestion.Entry.Option} which unfortunately inlines
+     * the output of
      * {@link #toInnerXContent(XContentBuilder, org.elasticsearch.common.xcontent.ToXContent.Params)}
      * of the included search hit. The output of the map is used to create the
      * actual SearchHit instance via {@link #createFromMap(Map)}
diff --git a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeAggregator.java b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeAggregator.java
index 2cde321230ebc..ab529ac033e73 100644
--- a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeAggregator.java
+++ b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeAggregator.java
@@ -200,7 +200,7 @@ public void collect(int doc, long bucket) throws IOException {
 
     /**
      * Replay the documents that might contain a top bucket and pass top buckets to
-     * the {@link this#deferredCollectors}.
+     * the {@link #deferredCollectors}.
      */
     private void runDeferredCollections() throws IOException {
         final boolean needsScores = needsScores();
diff --git a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeValuesCollectorQueue.java b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeValuesCollectorQueue.java
index b7b29a8841489..38e22296333ae 100644
--- a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeValuesCollectorQueue.java
+++ b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeValuesCollectorQueue.java
@@ -49,7 +49,7 @@ final class CompositeValuesCollectorQueue implements Releasable {
      *
      * @param sources The list of {@link CompositeValuesSourceConfig} to build the composite buckets.
      * @param size The number of composite buckets to keep.
-     * @param afterKey
+     * @param afterKey composite key
      */
     CompositeValuesCollectorQueue(BigArrays bigArrays, SingleDimensionValuesSource<?>[] sources, int size, CompositeKey afterKey) {
         this.bigArrays = bigArrays;
diff --git a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/SingleDimensionValuesSource.java b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/SingleDimensionValuesSource.java
index 1718bb4204879..c73820fc32a78 100644
--- a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/SingleDimensionValuesSource.java
+++ b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/SingleDimensionValuesSource.java
@@ -74,7 +74,7 @@ abstract class SingleDimensionValuesSource<T extends Comparable<T>> implements R
      * The current value is filled by a {@link LeafBucketCollector} that visits all the
      * values of each document. This method saves this current value in a slot and should only be used
      * in the context of a collection.
-     * See {@link this#getLeafCollector}.
+     * See {@link #getLeafCollector}.
      */
     abstract void copyCurrent(int slot);
 
@@ -87,7 +87,7 @@ abstract class SingleDimensionValuesSource<T extends Comparable<T>> implements R
      * The current value is filled by a {@link LeafBucketCollector} that visits all the
      * values of each document. This method compares this current value with the value present in
      * the provided slot and should only be used in the context of a collection.
-     * See {@link this#getLeafCollector}.
+     * See {@link #getLeafCollector}.
      */
     abstract int compareCurrent(int slot);
 
@@ -95,7 +95,7 @@ abstract class SingleDimensionValuesSource<T extends Comparable<T>> implements R
      * The current value is filled by a {@link LeafBucketCollector} that visits all the
      * values of each document. This method compares this current value with the after value
      * set on this source and should only be used in the context of a collection.
-     * See {@link this#getLeafCollector}.
+     * See {@link #getLeafCollector}.
      */
     abstract int compareCurrentWithAfter();
 
@@ -120,7 +120,7 @@ T getAfter() {
      * Creates a {@link LeafBucketCollector} that extracts all values from a document and invokes
      * {@link LeafBucketCollector#collect} on the provided <code>next</code> collector for each of them.
      * The current value of this source is set on each call and can be accessed by <code>next</code> via
-     * the {@link this#copyCurrent(int)} and {@link this#compareCurrent(int)} methods. Note that these methods
+     * the {@link #copyCurrent(int)} and {@link #compareCurrent(int)} methods. Note that these methods
      * are only valid when invoked from the {@link LeafBucketCollector} created in this source.
      */
     abstract LeafBucketCollector getLeafCollector(LeafReaderContext context, LeafBucketCollector next) throws IOException;
diff --git a/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java b/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java
index 0efeae29c3cce..170ea6cf9313d 100644
--- a/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java
+++ b/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java
@@ -863,7 +863,7 @@ public void testEnsureNoSelfReferences() throws IOException {
 
     /**
      * Test that the same map written multiple times do not trigger the self-reference check in
-     * {@link CollectionUtils#ensureNoSelfReferences(Object)}
+     * {@link CollectionUtils#ensureNoSelfReferences(Object, String)} (Object)}
      */
     public void testRepeatedMapsAndNoSelfReferences() throws Exception {
         Map<String, Object> mapB = singletonMap("b", "B");
diff --git a/server/src/test/java/org/elasticsearch/index/mapper/package-info.java b/server/src/test/java/org/elasticsearch/index/mapper/package-info.java
index 4221a5d4a9668..9a06e56a820a5 100644
--- a/server/src/test/java/org/elasticsearch/index/mapper/package-info.java
+++ b/server/src/test/java/org/elasticsearch/index/mapper/package-info.java
@@ -19,9 +19,7 @@
 
 /**
  * Mappings. Mappings define the way that documents should be translated to
- * Lucene indices, for instance how the
- * {@link org.elasticsearch.index.mapper.UidFieldMapper document identifier}
- * should be indexed, whether a string field should be indexed as a
+ * Lucene indices, for instance whether a string field should be indexed as a
  * {@link org.elasticsearch.index.mapper.TextFieldMapper text} or
  * {@link org.elasticsearch.index.mapper.KeywordFieldMapper keyword} field,
  * etc. This parsing is done by the
diff --git a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramIT.java b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramIT.java
index 26e6f4c076553..c40e3b73c6606 100644
--- a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramIT.java
+++ b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramIT.java
@@ -1345,8 +1345,6 @@ public void testExceptionOnNegativeInterval() {
      * https://github.com/elastic/elasticsearch/issues/31392 demonstrates an edge case where a date field mapping with
      * "format" = "epoch_millis" can lead for the date histogram aggregation to throw an error if a non-UTC time zone
      * with daylight savings time is used. This test was added to check this is working now
-     * @throws ExecutionException
-     * @throws InterruptedException
      */
     public void testRewriteTimeZone_EpochMillisFormat() throws InterruptedException, ExecutionException {
         String index = "test31392";
diff --git a/test/framework/src/main/java/org/elasticsearch/index/shard/IndexShardTestCase.java b/test/framework/src/main/java/org/elasticsearch/index/shard/IndexShardTestCase.java
index 9b21af713701a..5a8e91841c5a7 100644
--- a/test/framework/src/main/java/org/elasticsearch/index/shard/IndexShardTestCase.java
+++ b/test/framework/src/main/java/org/elasticsearch/index/shard/IndexShardTestCase.java
@@ -275,7 +275,7 @@ protected IndexShard newShard(ShardRouting routing, IndexMetaData indexMetaData,
      * @param indexMetaData          indexMetaData for the shard, including any mapping
      * @param indexSearcherWrapper   an optional wrapper to be used during searchers
      * @param globalCheckpointSyncer callback for syncing global checkpoints
-     * @param indexEventListener
+     * @param indexEventListener     index even listener
      * @param listeners              an optional set of listeners to add to the shard
      */
     protected IndexShard newShard(ShardRouting routing, ShardPath shardPath, IndexMetaData indexMetaData,
diff --git a/test/framework/src/main/java/org/elasticsearch/test/AbstractQueryTestCase.java b/test/framework/src/main/java/org/elasticsearch/test/AbstractQueryTestCase.java
index 48301fa5746e2..a2acc5371a19e 100644
--- a/test/framework/src/main/java/org/elasticsearch/test/AbstractQueryTestCase.java
+++ b/test/framework/src/main/java/org/elasticsearch/test/AbstractQueryTestCase.java
@@ -132,7 +132,6 @@ protected String[] shuffleProtectedFields() {
      * To find the right position in the root query, we add a marker as `queryName` which
      * all query builders support. The added bogus field after that should trigger the exception.
      * Queries that allow arbitrary field names at this level need to override this test.
-     * @throws IOException
      */
     public void testUnknownField() throws IOException {
         String marker = "#marker#";
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/license/ExpirationCallback.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/license/ExpirationCallback.java
index 26bec9e62948f..d3916f9dd3ab1 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/license/ExpirationCallback.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/license/ExpirationCallback.java
@@ -134,8 +134,8 @@ final TimeValue delay(long expirationDate, long now) {
     }
 
     /**
-     * {@link SchedulerEngine.Schedule#nextScheduledTimeAfter(long, long)} with respect to
-     * license expiry date
+     * {@link org.elasticsearch.xpack.core.scheduler.SchedulerEngine.Schedule#nextScheduledTimeAfter(long, long)}
+     * with respect to license expiry date
      */
     public final long nextScheduledTimeForExpiry(long expiryDate, long startTime, long time) {
         TimeValue delay = delay(expiryDate, time);
@@ -169,4 +169,4 @@ public final String toString() {
                 orientation.name(), TimeValue.timeValueMillis(min), TimeValue.timeValueMillis(max),
                 TimeValue.timeValueMillis(frequency));
     }
-}
\ No newline at end of file
+}
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/DerParser.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/DerParser.java
index fedbbb3194724..ae15c70e97b9b 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/DerParser.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/DerParser.java
@@ -87,7 +87,8 @@ Asn1Object readAsn1Object() throws IOException {
      * Decode the length of the field. Can only support length
      * encoding up to 4 octets.
      * <p>
-     * <p/>In BER/DER encoding, length can be encoded in 2 forms,
+     *          In BER/DER encoding, length can be encoded in 2 forms:
+     * </p>
      * <ul>
      * <li>Short form. One octet. Bit 8 has value "0" and bits 7-1
      * give the length.
@@ -100,7 +101,6 @@ Asn1Object readAsn1Object() throws IOException {
      * </ul>
      *
      * @return The length as integer
-     * @throws IOException
      */
     private int getLength() throws IOException {
 
@@ -145,7 +145,8 @@ static class Asn1Object {
          * Construct a ASN.1 TLV. The TLV could be either a
          * constructed or primitive entity.
          * <p>
-         * <p/>The first byte in DER encoding is made of following fields,
+         *     The first byte in DER encoding is made of following fields:
+         * </p>
          * <pre>
          * -------------------------------------------------
          * |Bit 8|Bit 7|Bit 6|Bit 5|Bit 4|Bit 3|Bit 2|Bit 1|
@@ -192,7 +193,6 @@ public boolean isConstructed() {
          * For constructed field, return a parser for its content.
          *
          * @return A parser for the construct.
-         * @throws IOException
          */
         public DerParser getParser() throws IOException {
             if (!isConstructed())
@@ -205,7 +205,6 @@ public DerParser getParser() throws IOException {
          * Get the value as integer
          *
          * @return BigInteger
-         * @throws IOException
          */
         public BigInteger getInteger() throws IOException {
             if (type != DerParser.INTEGER)
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/PemUtils.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/PemUtils.java
index 9ff44d0135ffa..d959c017e0a35 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/PemUtils.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/PemUtils.java
@@ -108,7 +108,6 @@ public static PrivateKey readPrivateKey(Path keyPath, Supplier<char[]> passwordS
      * Removes the EC Headers that OpenSSL adds to EC private keys as the information in them
      * is redundant
      *
-     * @param bReader
      * @throws IOException if the EC Parameter footer is missing
      */
     private static BufferedReader removeECHeaders(BufferedReader bReader) throws IOException {
@@ -133,7 +132,6 @@ private static BufferedReader removeECHeaders(BufferedReader bReader) throws IOE
      * Removes the DSA Params Headers that OpenSSL adds to DSA private keys as the information in them
      * is redundant
      *
-     * @param bReader
      * @throws IOException if the EC Parameter footer is missing
      */
     private static BufferedReader removeDsaHeaders(BufferedReader bReader) throws IOException {
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/RestrictedTrustManager.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/RestrictedTrustManager.java
index c49692dda98c1..8a82694785a28 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/RestrictedTrustManager.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/RestrictedTrustManager.java
@@ -132,7 +132,7 @@ private Set<String> readCommonNames(X509Certificate certificate) throws Certific
      * Decodes the otherName CN from the certificate
      *
      * @param value       The DER Encoded Subject Alternative Name
-     * @param certificate
+     * @param certificate The certificate
      * @return the CN or null if it could not be parsed
      */
     private String decodeDerValue(byte[] value, X509Certificate certificate) {
diff --git a/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/job/RollupIndexer.java b/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/job/RollupIndexer.java
index 5abd701ce4b2e..a07f1e7d32e7c 100644
--- a/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/job/RollupIndexer.java
+++ b/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/job/RollupIndexer.java
@@ -405,7 +405,8 @@ private CompositeAggregationBuilder createCompositeBuilder(RollupJobConfig confi
     }
 
     /**
-     * Creates the range query that limits the search to documents that appear before the maximum allowed time (see {@link this#maxBoundary}
+     * Creates the range query that limits the search to documents that appear before the maximum allowed time
+     * (see {@link #maxBoundary}
      * and on or after the last processed time.
      * @param position The current position of the pagination
      * @return The range query to execute
diff --git a/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/support/RestorableContextClassLoader.java b/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/support/RestorableContextClassLoader.java
index f2e36ebf98273..95c68eab9c28a 100644
--- a/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/support/RestorableContextClassLoader.java
+++ b/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/support/RestorableContextClassLoader.java
@@ -12,7 +12,7 @@
 import org.elasticsearch.SpecialPermission;
 
 /**
- * A <em>try-with-resource</em> compatible object for configuring a thread {@link Thread#contextClassLoader}.
+ * A <em>try-with-resource</em> compatible object for configuring a thread {@link Thread#getContextClassLoader()}.
  * On construction this class will set the current (or provided) thread's context class loader.
  * On {@link #close()}, it restores the previous value of the class loader.
  */
diff --git a/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/saml/SamlTestCase.java b/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/saml/SamlTestCase.java
index 51a6d8732a5b3..adaba34a73aa3 100644
--- a/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/saml/SamlTestCase.java
+++ b/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/saml/SamlTestCase.java
@@ -64,7 +64,6 @@ public static void restoreLocale() throws Exception {
      * Generates signed certificate and associates with generated key pair.
      * @see #readRandomKeyPair(String)
      * @return X509Certificate a signed certificate, it's PrivateKey {@link Tuple}
-     * @throws Exception
      */
     protected static Tuple<X509Certificate, PrivateKey> readRandomKeyPair() throws Exception {
         return readRandomKeyPair("RSA");
@@ -73,9 +72,7 @@ protected static Tuple<X509Certificate, PrivateKey> readRandomKeyPair() throws E
     /**
      * Reads a key pair and associated certificate for given algorithm and key length
      * For testing, for "EC" algorithm 256 key size is used, others use 2048 as default.
-     * @param algorithm
-     * @return X509Certificate a signed certificate, it's PrivateKey {@link Tuple}
-     * @throws Exception
+     * @return X509Certificate a signed certificate, it's PrivateKey
      */
     protected static Tuple<X509Certificate, PrivateKey> readRandomKeyPair(String algorithm) throws Exception {
         int keySize;
diff --git a/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/Range.java b/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/Range.java
index 54d541ab406b7..c17e9634492a1 100644
--- a/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/Range.java
+++ b/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/Range.java
@@ -87,7 +87,7 @@ public Object fold() {
     }
 
     /**
-     * Check whether the boundaries are invalid ( upper < lower) or not.
+     * Check whether the boundaries are invalid ( upper &lt; lower) or not.
      * If they do, the value does not have to be evaluate.
      */
     private boolean areBoundariesInvalid() {
@@ -139,4 +139,4 @@ public String toString() {
         sb.append(upper);
         return sb.toString();
     }
-}
\ No newline at end of file
+}
diff --git a/x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/IndexAuditUpgradeIT.java b/x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/IndexAuditUpgradeIT.java
index 7c81a7141a991..92a8c3d2f830f 100644
--- a/x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/IndexAuditUpgradeIT.java
+++ b/x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/IndexAuditUpgradeIT.java
@@ -87,7 +87,6 @@ private void assertNumUniqueNodeNameBuckets(int numBuckets) throws Exception {
 
     /**
      * Has the master been upgraded to the new version?
-     * @throws IOException
      */
     private boolean masterIsNewVersion() throws IOException {
         Map<?, ?> map = entityAsMap(client().performRequest("GET", "/_nodes/_master"));