code: public Queue<SessionSchedulable> getPreemptQueue() {
      if (preemptQueue == null) {
  
        ScheduleComparator comparator = null;
        switch (configManager.getPoolComparator(poolInfo)) {
        case FIFO:
          comparator = ScheduleComparator.FIFO_PREEMPT;
          break;
        case FAIR:
          comparator = ScheduleComparator.FAIR_PREEMPT;
          break;
        case DEADLINE:
          comparator = ScheduleComparator.DEADLINE_PREEMPT;
          break;
        default:
          throw new IllegalArgumentException("Unknown comparator");
        }
  
        preemptQueue = createSessionQueue(comparator);
      }
      return preemptQueue;
    }
docs: Get the queue of sessions sorted for preemption
  @return the queue of sessions sorted for preemption