code: @Override
    public void onStageTransition(JobExecutionState state, String previousStage, String newStage) {
      try {
        _dispatcher.execCallbacks(new StageTransitionCallback(state, previousStage, newStage));
      } catch (InterruptedException e) {
        _dispatcher.getLog().warn("onStageTransition interrupted.");
      }
    }
docs: {@inheritDoc}