code: public JobStatusListener createActivatorDeactivator() {
  		synchronized (lock) {
  			if (shutdown) {
  				throw new IllegalArgumentException("Checkpoint coordinator is shut down");
  			}
  
  			if (jobStatusListener == null) {
  				jobStatusListener = new CheckpointCoordinatorDeActivator(this);
  			}
  
  			return jobStatusListener;
  		}
  	}
docs: ------------------------------------------------------------------------