Merge branch '6.x' into ccr-6.x

* 6.x:
  Do not check for object existence when deleting repository index files (#31680)
  Remove extra check for object existence in repository-gcs read object (#31661)
  [Test] Clean up some repository-s3 tests (#31601)
  Merge AzureStorageService and AzureStorageServiceImpl and clean up tests (#31607)
  [Docs] Use capital letters in section headings (#31678)
  [DOCS] Add PQL language Plugin (#31237)
  [DOCS] Fix licensing API details (#31667)
  Fix CreateSnapshotRequestTests Failure (#31630)
  Add Create Snapshot to High-Level Rest Client (#31215)
  Add MultiSearchTemplate support to High Level Rest client (#31662)
  SQL: Refactor package names of sql-proto and sql-shared-proto projects (#31622)
  [TEST] Mute failing NamingConventionsTaskIT tests
  [DOCS] Replace CONFIG_DIR with ES_PATH_CONF (#31635)
  Add test for low-level client round-robin behaviour (#31616)
  HLRest: Fix test for explain API
  Add explain API to high-level REST client (#31387)

buildSrc/src/test/java/org/elasticsearch/gradle/precommit/NamingConventionsTaskIT.java

@@ -4,6 +4,7 @@
 import org.gradle.testkit.runner.BuildResult;
 import org.gradle.testkit.runner.GradleRunner;
 import org.gradle.testkit.runner.TaskOutcome;
+import org.junit.Ignore;
 
 import java.util.Arrays;
 
@@ -20,6 +21,7 @@ public void testPluginCanBeApplied() {
         assertTrue(result.getOutput().contains("build plugin can be applied"));
     }
 
+    @Ignore("AwaitsFix : https://github.com/elastic/elasticsearch/issues/31665")
     public void testNameCheckFailsAsItShould() {
         BuildResult result = GradleRunner.create()
             .withProjectDir(getProjectDir("namingConventionsSelfTest"))
@@ -44,6 +46,7 @@ public void testNameCheckFailsAsItShould() {
         }
     }
 
+    @Ignore("AwaitsFix : https://github.com/elastic/elasticsearch/issues/31665")
     public void testNameCheckFailsAsItShouldWithMain() {
         BuildResult result = GradleRunner.create()
             .withProjectDir(getProjectDir("namingConventionsSelfTest"))

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

@@ -37,6 +37,7 @@
 import org.elasticsearch.action.admin.cluster.repositories.put.PutRepositoryRequest;
 import org.elasticsearch.action.admin.cluster.repositories.verify.VerifyRepositoryRequest;
 import org.elasticsearch.action.admin.cluster.settings.ClusterUpdateSettingsRequest;
+import org.elasticsearch.action.admin.cluster.snapshots.create.CreateSnapshotRequest;
 import org.elasticsearch.action.admin.cluster.storedscripts.DeleteStoredScriptRequest;
 import org.elasticsearch.action.admin.cluster.storedscripts.GetStoredScriptRequest;
 import org.elasticsearch.action.admin.cluster.snapshots.delete.DeleteSnapshotRequest;
@@ -65,14 +66,15 @@
 import org.elasticsearch.action.admin.indices.validate.query.ValidateQueryRequest;
 import org.elasticsearch.action.bulk.BulkRequest;
 import org.elasticsearch.action.delete.DeleteRequest;
+import org.elasticsearch.action.explain.ExplainRequest;
 import org.elasticsearch.action.fieldcaps.FieldCapabilitiesRequest;
 import org.elasticsearch.action.get.GetRequest;
 import org.elasticsearch.action.get.MultiGetRequest;
 import org.elasticsearch.action.index.IndexRequest;
 import org.elasticsearch.action.ingest.DeletePipelineRequest;
-import org.elasticsearch.action.ingest.PutPipelineRequest;
 import org.elasticsearch.action.ingest.GetPipelineRequest;
 import org.elasticsearch.action.ingest.SimulatePipelineRequest;
+import org.elasticsearch.action.ingest.PutPipelineRequest;
 import org.elasticsearch.action.search.ClearScrollRequest;
 import org.elasticsearch.action.search.MultiSearchRequest;
 import org.elasticsearch.action.search.SearchRequest;
@@ -100,6 +102,7 @@
 import org.elasticsearch.index.VersionType;
 import org.elasticsearch.index.rankeval.RankEvalRequest;
 import org.elasticsearch.rest.action.search.RestSearchAction;
+import org.elasticsearch.script.mustache.MultiSearchTemplateRequest;
 import org.elasticsearch.script.mustache.SearchTemplateRequest;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.tasks.TaskId;
@@ -610,6 +613,21 @@ static Request searchTemplate(SearchTemplateRequest searchTemplateRequest) throw
         request.setEntity(createEntity(searchTemplateRequest, REQUEST_BODY_CONTENT_TYPE));
         return request;
     }
+
+    static Request multiSearchTemplate(MultiSearchTemplateRequest multiSearchTemplateRequest) throws IOException {
+        Request request = new Request(HttpPost.METHOD_NAME, "/_msearch/template");
+
+        Params params = new Params(request);
+        params.putParam(RestSearchAction.TYPED_KEYS_PARAM, "true");
+        if (multiSearchTemplateRequest.maxConcurrentSearchRequests() != MultiSearchRequest.MAX_CONCURRENT_SEARCH_REQUESTS_DEFAULT) {
+            params.putParam("max_concurrent_searches", Integer.toString(multiSearchTemplateRequest.maxConcurrentSearchRequests()));
+        }
+
+        XContent xContent = REQUEST_BODY_CONTENT_TYPE.xContent();
+        byte[] source = MultiSearchTemplateRequest.writeMultiLineFormat(multiSearchTemplateRequest, xContent);
+        request.setEntity(new ByteArrayEntity(source, createContentType(xContent.type())));
+        return request;
+    }    
 
     static Request existsAlias(GetAliasesRequest getAliasesRequest) {
         if ((getAliasesRequest.indices() == null || getAliasesRequest.indices().length == 0) &&
@@ -627,6 +645,19 @@ static Request existsAlias(GetAliasesRequest getAliasesRequest) {
         return request;
     }
 
+    static Request explain(ExplainRequest explainRequest) throws IOException {
+        Request request = new Request(HttpGet.METHOD_NAME,
+            endpoint(explainRequest.index(), explainRequest.type(), explainRequest.id(), "_explain"));
+
+        Params params = new Params(request);
+        params.withStoredFields(explainRequest.storedFields());
+        params.withFetchSourceContext(explainRequest.fetchSourceContext());
+        params.withRouting(explainRequest.routing());
+        params.withPreference(explainRequest.preference());
+        request.setEntity(createEntity(explainRequest, REQUEST_BODY_CONTENT_TYPE));
+        return request;
+    }
+
     static Request fieldCaps(FieldCapabilitiesRequest fieldCapabilitiesRequest) {
         String[] indices = fieldCapabilitiesRequest.indices();
         Request request = new Request(HttpGet.METHOD_NAME, endpoint(indices, "_field_caps"));
@@ -877,6 +908,19 @@ static Request verifyRepository(VerifyRepositoryRequest verifyRepositoryRequest)
         return request;
     }
 
+    static Request createSnapshot(CreateSnapshotRequest createSnapshotRequest) throws IOException {
+        String endpoint = new EndpointBuilder().addPathPart("_snapshot")
+            .addPathPart(createSnapshotRequest.repository())
+            .addPathPart(createSnapshotRequest.snapshot())
+            .build();
+        Request request = new Request(HttpPut.METHOD_NAME, endpoint);
+        Params params = new Params(request);
+        params.withMasterTimeout(createSnapshotRequest.masterNodeTimeout());
+        params.withWaitForCompletion(createSnapshotRequest.waitForCompletion());
+        request.setEntity(createEntity(createSnapshotRequest, REQUEST_BODY_CONTENT_TYPE));
+        return request;
+    }
+
     static Request deleteSnapshot(DeleteSnapshotRequest deleteSnapshotRequest) {
         String endpoint = new EndpointBuilder().addPathPartAsIs("_snapshot")
             .addPathPart(deleteSnapshotRequest.repository())

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

@@ -34,6 +34,8 @@
 import org.elasticsearch.action.bulk.BulkResponse;
 import org.elasticsearch.action.delete.DeleteRequest;
 import org.elasticsearch.action.delete.DeleteResponse;
+import org.elasticsearch.action.explain.ExplainRequest;
+import org.elasticsearch.action.explain.ExplainResponse;
 import org.elasticsearch.action.fieldcaps.FieldCapabilitiesRequest;
 import org.elasticsearch.action.fieldcaps.FieldCapabilitiesResponse;
 import org.elasticsearch.action.get.GetRequest;
@@ -66,6 +68,8 @@
 import org.elasticsearch.plugins.spi.NamedXContentProvider;
 import org.elasticsearch.rest.BytesRestResponse;
 import org.elasticsearch.rest.RestStatus;
+import org.elasticsearch.script.mustache.MultiSearchTemplateRequest;
+import org.elasticsearch.script.mustache.MultiSearchTemplateResponse;
 import org.elasticsearch.script.mustache.SearchTemplateRequest;
 import org.elasticsearch.script.mustache.SearchTemplateResponse;
 import org.elasticsearch.search.aggregations.Aggregation;
@@ -899,6 +903,42 @@ public final void searchTemplateAsync(SearchTemplateRequest searchTemplateReques
             SearchTemplateResponse::fromXContent, listener, emptySet());
     }
 
+    /**
+     * Executes a request using the Explain API.
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-explain.html">Explain API on elastic.co</a>
+     * @param explainRequest the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @return the response
+     * @throws IOException in case there is a problem sending the request or parsing back the response
+     */
+    public final ExplainResponse explain(ExplainRequest explainRequest, RequestOptions options) throws IOException {
+        return performRequest(explainRequest, RequestConverters::explain, options,
+            response -> {
+                CheckedFunction<XContentParser, ExplainResponse, IOException> entityParser =
+                    parser -> ExplainResponse.fromXContent(parser, convertExistsResponse(response));
+                return parseEntity(response.getEntity(), entityParser);
+            },
+            singleton(404));
+    }
+
+    /**
+     * Asynchronously executes a request using the Explain API.
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-explain.html">Explain API on elastic.co</a>
+     * @param explainRequest the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @param listener the listener to be notified upon request completion
+     */
+    public final void explainAsync(ExplainRequest explainRequest, RequestOptions options, ActionListener<ExplainResponse> listener) {
+        performRequestAsync(explainRequest, RequestConverters::explain, options,
+            response -> {
+                CheckedFunction<XContentParser, ExplainResponse, IOException> entityParser =
+                    parser -> ExplainResponse.fromXContent(parser, convertExistsResponse(response));
+                return parseEntity(response.getEntity(), entityParser);
+            },
+            listener, singleton(404));
+    }
+
     /**
      * Executes a request using the Ranking Evaluation API.
      * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-rank-eval.html">Ranking Evaluation API
@@ -939,6 +979,32 @@ public final void rankEvalAsync(RankEvalRequest rankEvalRequest, RequestOptions
                 emptySet());
     }
 
+
+    /**
+     * Executes a request using the Multi Search Template API.
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/multi-search-template.html">Multi Search Template API
+     * on elastic.co</a>.
+     */
+    public final MultiSearchTemplateResponse multiSearchTemplate(MultiSearchTemplateRequest multiSearchTemplateRequest,
+            RequestOptions options) throws IOException {
+        return performRequestAndParseEntity(multiSearchTemplateRequest, RequestConverters::multiSearchTemplate,
+                options, MultiSearchTemplateResponse::fromXContext, emptySet());        
+    }   
+
+    /**
+     * Asynchronously executes a request using the Multi Search Template API
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/multi-search-template.html">Multi Search Template API
+     * on elastic.co</a>.
+     */
+    public final void multiSearchTemplateAsync(MultiSearchTemplateRequest multiSearchTemplateRequest,
+                                          RequestOptions options,
+                                          ActionListener<MultiSearchTemplateResponse> listener) {
+        performRequestAsyncAndParseEntity(multiSearchTemplateRequest, RequestConverters::multiSearchTemplate,
+            options, MultiSearchTemplateResponse::fromXContext, listener, emptySet());
+    }    
+
     /**
      * Asynchronously executes a request using the Ranking Evaluation API.
      *

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

@@ -28,6 +28,8 @@
 import org.elasticsearch.action.admin.cluster.repositories.put.PutRepositoryResponse;
 import org.elasticsearch.action.admin.cluster.repositories.verify.VerifyRepositoryRequest;
 import org.elasticsearch.action.admin.cluster.repositories.verify.VerifyRepositoryResponse;
+import org.elasticsearch.action.admin.cluster.snapshots.create.CreateSnapshotRequest;
+import org.elasticsearch.action.admin.cluster.snapshots.create.CreateSnapshotResponse;
 import org.elasticsearch.action.admin.cluster.snapshots.delete.DeleteSnapshotRequest;
 import org.elasticsearch.action.admin.cluster.snapshots.delete.DeleteSnapshotResponse;
 
@@ -164,6 +166,30 @@ public void verifyRepositoryAsync(VerifyRepositoryRequest verifyRepositoryReques
             VerifyRepositoryResponse::fromXContent, listener, emptySet());
     }
 
+    /**
+     * Creates a snapshot.
+     * <p>
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-snapshots.html"> Snapshot and Restore
+     * API on elastic.co</a>
+     */
+    public CreateSnapshotResponse createSnapshot(CreateSnapshotRequest createSnapshotRequest, RequestOptions options)
+        throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(createSnapshotRequest, RequestConverters::createSnapshot, options,
+            CreateSnapshotResponse::fromXContent, emptySet());
+    }
+
+    /**
+     * Asynchronously creates a snapshot.
+     * <p>
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-snapshots.html"> Snapshot and Restore
+     * API on elastic.co</a>
+     */
+    public void createSnapshotAsync(CreateSnapshotRequest createSnapshotRequest, RequestOptions options,
+                                    ActionListener<CreateSnapshotResponse> listener) {
+        restHighLevelClient.performRequestAsyncAndParseEntity(createSnapshotRequest, RequestConverters::createSnapshot, options,
+            CreateSnapshotResponse::fromXContent, listener, emptySet());
+    }
+
     /**
      * Deletes a snapshot.
      * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-snapshots.html"> Snapshot and Restore