Leftover from https://github.com/elastic/elasticsearch/pull/35964 (#36030)

x-pack/plugin/sql/sql-proto/src/main/java/org/elasticsearch/xpack/sql/proto/Protocol.java

@@ -30,6 +30,8 @@ public final class Protocol {
     public static final String CLEAR_CURSOR_DEPRECATED_REST_ENDPOINT = "/_xpack/sql/close";
     public static final String SQL_QUERY_REST_ENDPOINT = "/_sql";
     public static final String SQL_QUERY_DEPRECATED_REST_ENDPOINT = "/_xpack/sql";
+    public static final String SQL_TRANSLATE_REST_ENDPOINT = "/_sql/translate";
+    public static final String SQL_TRANSLATE_DEPRECATED_REST_ENDPOINT = "/_xpack/sql/translate";
     public static final String SQL_STATS_REST_ENDPOINT = "/_sql/stats";
     public static final String SQL_STATS_DEPRECATED_REST_ENDPOINT = "/_xpack/sql/stats";
 }

x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/plugin/RestSqlTranslateAction.java

@@ -5,7 +5,9 @@
  */
 package org.elasticsearch.xpack.sql.plugin;
 
+import org.apache.logging.log4j.LogManager;
 import org.elasticsearch.client.node.NodeClient;
+import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.rest.BaseRestHandler;
@@ -15,6 +17,7 @@ import org.elasticsearch.rest.action.RestToXContentListener;
 import org.elasticsearch.xpack.sql.action.SqlTranslateAction;
 import org.elasticsearch.xpack.sql.action.SqlTranslateRequest;
 import org.elasticsearch.xpack.sql.proto.Mode;
+import org.elasticsearch.xpack.sql.proto.Protocol;
 
 import java.io.IOException;
 
@@ -25,10 +28,19 @@ import static org.elasticsearch.rest.RestRequest.Method.POST;
  * REST action for translating SQL queries into ES requests
  */
 public class RestSqlTranslateAction extends BaseRestHandler {
+    
+    private static final DeprecationLogger deprecationLogger = new DeprecationLogger(LogManager.getLogger(RestSqlTranslateAction.class));
+    
     public RestSqlTranslateAction(Settings settings, RestController controller) {
         super(settings);
-        controller.registerHandler(GET, "/_sql/translate", this);
-        controller.registerHandler(POST, "/_sql/translate", this);
+        // TODO: remove deprecated endpoint in 8.0.0
+        controller.registerWithDeprecatedHandler(
+                GET, Protocol.SQL_TRANSLATE_REST_ENDPOINT, this,
+                GET, Protocol.SQL_TRANSLATE_DEPRECATED_REST_ENDPOINT, deprecationLogger);
+        // TODO: remove deprecated endpoint in 8.0.0
+        controller.registerWithDeprecatedHandler(
+                POST, Protocol.SQL_TRANSLATE_REST_ENDPOINT, this,
+                POST, Protocol.SQL_TRANSLATE_DEPRECATED_REST_ENDPOINT, deprecationLogger);
     }
 
     @Override