Add a deprecation message if a REST wrapper implementing plugin presents (#66827)

* Add a deprecation message if a REST wrapper implementing plugin presents

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -227,6 +227,8 @@ import org.elasticsearch.common.NamedRegistry;
 import org.elasticsearch.common.inject.AbstractModule;
 import org.elasticsearch.common.inject.TypeLiteral;
 import org.elasticsearch.common.inject.multibindings.MapBinder;
+import org.elasticsearch.common.logging.DeprecationCategory;
+import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.IndexScopedSettings;
 import org.elasticsearch.common.settings.Settings;
@@ -392,6 +394,7 @@ import static java.util.Collections.unmodifiableMap;
 public class ActionModule extends AbstractModule {
 
     private static final Logger logger = LogManager.getLogger(ActionModule.class);
+    private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(logger.getName());
 
     private final Settings settings;
     private final IndexNameExpressionResolver indexNameExpressionResolver;
@@ -436,6 +439,13 @@ public class ActionModule extends AbstractModule {
                     throw new IllegalArgumentException("Cannot have more than one plugin implementing a REST wrapper");
                 }
                 restWrapper = newRestWrapper;
+                if (restWrapper.getClass().getCanonicalName() == null ||
+                    restWrapper.getClass().getCanonicalName().startsWith("org.elasticsearch") == false) {
+                    deprecationLogger.deprecate(DeprecationCategory.PLUGINS, "3rd_party_rest_deprecation", "The " +
+                        plugin.getClass().getName() + "plugin installs a custom REST wrapper. This functionality is deprecated and will " +
+                        "not be possible in Elasticsearch 8.0. If this plugin is intended to provide security features for Elasticsearch " +
+                        "then you should switch to using the built-in Elasticsearch features instead.");
+                }
             }
         }
         mappingRequestValidators = new RequestValidators<>(