}
            } finally {
              lock.unlock();
            }
          });
    }

    @Override
    protected final void doStop() {
      // Both requireNonNull calls are safe because doStop can run only after a successful doStart.
      requireNonNull(runningTask);
      requireNonNull(executorService);
      runningTask.cancel(false);
      executorService.execute(

              }
            } finally {
              lock.unlock();
            }
          });
    }

    @Override
    protected final void doStop() {
      // Both requireNonNull calls are safe because doStop can run only after a successful doStart.
      requireNonNull(runningTask);
      requireNonNull(executorService);
      runningTask.cancel(false);
      executorService.execute(