code: public Queue<PoolSchedulable> getPreemptQueue() {
      // TODO: For now, we support only one kind of scheduling.
      // Also note that FAIR is PRIORITY with equal priorities (by default)
      ScheduleComparator sPreempt = null;
      if (preemptQueue == null) {
        ScheduleComparator sc = configManager.getPoolGroupComparator(getName());
        if (sc == ScheduleComparator.PRIORITY) {
          sPreempt = ScheduleComparator.PRIORITY_PREEMPT;
        } else {
          throw new IllegalArgumentException("Unknown/misconfigured poolgroup");
        }
        preemptQueue = createPoolQueue(sPreempt);
      }
      return preemptQueue;
    }
docs: Get the queue of the pool sorted for preemption
  @return the queue of pool sorted for preemption