Deprecate the _termvector endpoint. (#36098)

This endpoint was replaced by _termvectors (plural) in #8484. We deprecated the relevant
transport client methods, but didn't introduce a deprecation warning. My plan was to add
a deprecation warning in 6.6, and stop supporting this endpoint in 7.0.

Author: jtibshirani

server/src/main/java/org/elasticsearch/rest/action/document/RestTermVectorsAction.java

@@ -19,9 +19,11 @@
 
 package org.elasticsearch.rest.action.document;
 
+import org.apache.logging.log4j.LogManager;
 import org.elasticsearch.action.termvectors.TermVectorsRequest;
 import org.elasticsearch.client.node.NodeClient;
 import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.VersionType;
@@ -43,18 +45,19 @@
  * TermVectorsRequest.
  */
 public class RestTermVectorsAction extends BaseRestHandler {
+    private static final DeprecationLogger deprecationLogger = new DeprecationLogger(
+        LogManager.getLogger(RestTermVectorsAction.class));
+
     public RestTermVectorsAction(Settings settings, RestController controller) {
         super(settings);
-        controller.registerHandler(GET, "/{index}/{type}/_termvectors", this);
-        controller.registerHandler(POST, "/{index}/{type}/_termvectors", this);
-        controller.registerHandler(GET, "/{index}/{type}/{id}/_termvectors", this);
-        controller.registerHandler(POST, "/{index}/{type}/{id}/_termvectors", this);
-
-        // we keep usage of _termvector as alias for now
-        controller.registerHandler(GET, "/{index}/{type}/_termvector", this);
-        controller.registerHandler(POST, "/{index}/{type}/_termvector", this);
-        controller.registerHandler(GET, "/{index}/{type}/{id}/_termvector", this);
-        controller.registerHandler(POST, "/{index}/{type}/{id}/_termvector", this);
+        controller.registerWithDeprecatedHandler(GET, "/{index}/{type}/_termvectors", this,
+            GET, "/{index}/{type}/_termvector", deprecationLogger);
+        controller.registerWithDeprecatedHandler(POST, "/{index}/{type}/_termvectors", this,
+            POST, "/{index}/{type}/_termvector", deprecationLogger);
+        controller.registerWithDeprecatedHandler(GET, "/{index}/{type}/{id}/_termvectors", this,
+            GET, "/{index}/{type}/{id}/_termvector", deprecationLogger);
+        controller.registerWithDeprecatedHandler(POST, "/{index}/{type}/{id}/_termvectors", this,
+            POST, "/{index}/{type}/{id}/_termvector", deprecationLogger);
     }
 
     @Override

server/src/test/java/org/elasticsearch/rest/action/document/RestTermVectorsActionTests.java

@@ -0,0 +1,67 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.rest.action.document;
+
+import org.elasticsearch.client.node.NodeClient;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.util.concurrent.ThreadContext;
+import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
+import org.elasticsearch.rest.RestChannel;
+import org.elasticsearch.rest.RestController;
+import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.RestRequest.Method;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.test.rest.FakeRestChannel;
+import org.elasticsearch.test.rest.FakeRestRequest;
+import org.elasticsearch.usage.UsageService;
+
+import java.util.Collections;
+
+import static org.mockito.Mockito.mock;
+
+public class RestTermVectorsActionTests extends ESTestCase {
+    private RestController controller;
+
+    public void setUp() throws Exception {
+        super.setUp();
+        controller = new RestController(Collections.emptySet(), null,
+            mock(NodeClient.class),
+            new NoneCircuitBreakerService(),
+            new UsageService());
+        new RestTermVectorsAction(Settings.EMPTY, controller);
+    }
+
+    public void testDeprecatedEndpoint() {
+        RestRequest request = new FakeRestRequest.Builder(xContentRegistry())
+            .withMethod(Method.POST)
+            .withPath("/some_index/some_type/some_id/_termvector")
+            .build();
+
+        performRequest(request);
+        assertWarnings("[POST /{index}/{type}/{id}/_termvector] is deprecated! Use" +
+            " [POST /{index}/{type}/{id}/_termvectors] instead.");
+    }
+
+    private void performRequest(RestRequest request) {
+        RestChannel channel = new FakeRestChannel(request, false, 1);
+        ThreadContext threadContext = new ThreadContext(Settings.EMPTY);
+        controller.dispatchRequest(request, channel, threadContext);
+    }
+}