code: @Override
      public void shutdown() {
          LOG.info("Begin to shutdown master");
          // Timer.cancelTimer(nimbus.getTimer());
          ITopologyActionNotifierPlugin nimbusNotify = data.getNimbusNotify();
          if (nimbusNotify != null)
              nimbusNotify.cleanup();
          LOG.info("Successfully shutdown master");
  
      }
docs: Shutdown nimbus