code: private void methodBasedSaveNamespace(boolean force, boolean uncompressed)
    throws AccessControlException, IOException {
      if (namenodeProtocolProxy.isMethodSupported(
          "saveNamespace", boolean.class, boolean.class)) {
        namenode.saveNamespace(force, uncompressed);
      } else {
        namenode.saveNamespace();
      }
    }
docs: Method-based save namespace