private final Object lock = new Object();

    /*
     * Conceptually, these two variables describe the executor being in
     * one of three states:
     *   - Active: shutdown == false
     *   - Shutdown: runningTasks > 0 and shutdown == true
     *   - Terminated: runningTasks == 0 and shutdown == true
     */
    @GuardedBy("lock")

    public abstract Object execute(String scriptType, String script);

    public void shutdown() {
        shutdownListener.onShutdown();
    }

    public void addShutdownListener(final ShutdownListener listener) {
        shutdownListener = listener;
    }

    public interface ShutdownListener {
        void onShutdown();
    }

    Request request = new Request.Builder()
        .url("ws://echo.websocket.org")
        .build();
    client.newWebSocket(request, this);

    // Trigger shutdown of the dispatcher's executor so this process exits immediately.
    client.dispatcher().executorService().shutdown();
  }

  @Override public void onOpen(WebSocket webSocket, Response response) {
    webSocket.send("Hello...");
    webSocket.send("...World!");

        this.repositorySystemProvider = requireNonNull(repositorySystemProvider);
    }

    @PreDestroy
    public void shutdown() {
        repositorySystemProvider.get().shutdown();
    }

 * the "running" state need to perform a periodic task. Subclasses can implement {@link #startUp},
 * {@link #shutDown} and also a {@link #runOneIteration} method that will be executed periodically.
 *
 * <p>This class uses the {@link ScheduledExecutorService} returned from {@link #executor} to run
 * the {@link #startUp} and {@link #shutDown} methods and also uses that service to schedule the

                  // which case we should skip right down to shutdown.
                  if (isRunning()) {
                    try {
                      AbstractExecutionThreadService.this.run();
                    } catch (Throwable t) {
                      restoreInterruptIfIsInterruptedException(t);
                      try {
                        shutDown();
                      } catch (Exception ignored) {

      ExecutionException e = assertThrows(ExecutionException.class, () -> f.get());
      assertThat(e).hasCauseThat().isInstanceOf(TimeoutException.class);
    } finally {
      executor.shutdown();
    }
  }

            method.invoke(null, (Object[]) null);
        } catch (final ClassNotFoundException e) {
            // ignore
        } catch (final Exception e) {
            logger.warn("Could not shutdown Commons HttpClient.", e);
        }
    }

      }
      barrier.await(); // release the threads!
      barrier.await(); // wait for them all to complete
      assertEquals(1, task.get().intValue());
      assertEquals(1, counter.get());
    }
    executor.shutdown();
  }

  @J2ktIncompatible
  @GwtIncompatible // blocking wait
  public void testToString() throws Exception {
    final CountDownLatch enterLatch = new CountDownLatch(1);

      File temp = TempFileCreator.INSTANCE.createTempFile("FileBackedOutputStream");
      if (resetOnFinalize) {
        // Finalizers are not guaranteed to be called on system shutdown;
        // this is insurance.
        temp.deleteOnExit();
      }
      try {
        FileOutputStream transfer = new FileOutputStream(temp);
        transfer.write(memory.getBuffer(), 0, memory.getCount());