}

      // If there's an existing AwaitIdleTask, use it. This is necessary when the executor is
      // shutdown but still busy as we can't enqueue in that case.
      val existingTask = activeTask
      if (existingTask is AwaitIdleTask) {
        return existingTask.latch
      }
      for (futureTask in futureTasks) {
        if (futureTask is AwaitIdleTask) {
          return futureTask.latch
        }