code: public Task getTask(ExecutionAttemptID executionAttemptID) {
  		TaskSlotMapping taskSlotMapping = taskSlotMappings.get(executionAttemptID);
  
  		if (taskSlotMapping != null) {
  			return taskSlotMapping.getTask();
  		} else {
  			return null;
  		}
  	}
docs: Get the task for the given execution attempt id. If none could be found, then return null.
  
  @param executionAttemptID identifying the requested task
  @return The task for the given execution attempt id if it exist; otherwise null