code: public synchronized boolean advanceToLastPostedRunnable() {
      long currentMaxTime = currentTime;
      for (ScheduledRunnable scheduled : runnables) {
        if (currentMaxTime < scheduled.scheduledTime) {
          currentMaxTime = scheduled.scheduledTime;
        }
      }
      return advanceTo(currentMaxTime);
    }
docs: Run all runnables in the queue, and any additional runnables they schedule that are scheduled
  before the latest scheduled runnable currently in the queue.
  
  @return True if a runnable was executed.