Fix unchecked cast in dynamic action map getter (#15394)

Signed-off-by: Daniel Widdis <widdis@gmail.com>

CHANGELOG.md

@@ -68,6 +68,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix range aggregation optimization ignoring top level queries ([#15194](https://github.com/opensearch-project/OpenSearch/pull/15194))
 - Fix incorrect parameter names in MinHash token filter configuration handling ([#15233](https://github.com/opensearch-project/OpenSearch/pull/15233))
 - Fix split response processor not included in allowlist ([#15393](https://github.com/opensearch-project/OpenSearch/pull/15393))
+- Fix unchecked cast in dynamic action map getter ([#15394](https://github.com/opensearch-project/OpenSearch/pull/15394))
 
 ### Security
 

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

@@ -1200,9 +1200,12 @@ public void unregisterDynamicRoute(NamedRoute route) {
          * @param route The {@link RestHandler.Route}.
          * @return the corresponding {@link RestSendToExtensionAction} if it is registered, null otherwise.
          */
-        @SuppressWarnings("unchecked")
         public RestSendToExtensionAction get(RestHandler.Route route) {
-            return routeRegistry.get(route);
+            if (route instanceof NamedRoute) {
+                return routeRegistry.get((NamedRoute) route);
+            }
+            // Only NamedRoutes are map keys so any other route is not in the map
+            return null;
         }
     }
 }

server/src/test/java/org/opensearch/action/DynamicActionRegistryTests.java

@@ -20,6 +20,7 @@
 import org.opensearch.extensions.action.ExtensionTransportAction;
 import org.opensearch.extensions.rest.RestSendToExtensionAction;
 import org.opensearch.rest.NamedRoute;
+import org.opensearch.rest.RestHandler;
 import org.opensearch.rest.RestRequest;
 import org.opensearch.tasks.Task;
 import org.opensearch.tasks.TaskManager;
@@ -85,13 +86,17 @@ public void testDynamicActionRegistryWithNamedRoutes() {
         RestSendToExtensionAction action2 = mock(RestSendToExtensionAction.class);
         NamedRoute r1 = new NamedRoute.Builder().method(RestRequest.Method.GET).path("/foo").uniqueName("foo").build();
         NamedRoute r2 = new NamedRoute.Builder().method(RestRequest.Method.PUT).path("/bar").uniqueName("bar").build();
+        RestHandler.Route r3 = new RestHandler.Route(RestRequest.Method.DELETE, "/foo");
 
         DynamicActionRegistry registry = new DynamicActionRegistry();
         registry.registerDynamicRoute(r1, action);
         registry.registerDynamicRoute(r2, action2);
 
         assertTrue(registry.isActionRegistered("foo"));
+        assertEquals(action, registry.get(r1));
         assertTrue(registry.isActionRegistered("bar"));
+        assertEquals(action2, registry.get(r2));
+        assertNull(registry.get(r3));
 
         registry.unregisterDynamicRoute(r2);