void triggerGetNextTask() {
        lock.lock();
        try {
          shouldRun = true;
          triggerRunCondition.signal();
        } finally {
          lock.unlock();
        }
      }
Note: this only works for testing the lack of invocations from the main thread.
llap-tez/src/test/org/apache/hadoop/hive/llap/tezplugins/TestLlapTaskSchedulerService.java