code: @VisibleForTesting
  	public boolean containsJob(JobID jobId) {
  		Preconditions.checkState(JobLeaderService.State.STARTED == state, "The service is currently not running.");
  
  		return jobLeaderServices.containsKey(jobId);
  	}
docs: Check whether the service monitors the given job.
  
  @param jobId identifying the job
  @return True if the given job is monitored; otherwise false