fix phpdoc

src/Symfony/Component/Security/Http/Authorization/AccessDeniedHandlerInterface.php

@@ -26,7 +26,7 @@ interface AccessDeniedHandlerInterface
     /**
      * Handles an access denied failure.
      *
-     * @return Response may return null
+     * @return Response|null
      */
     public function handle(Request $request, AccessDeniedException $accessDeniedException);
 }