* <p>This method should return promptly; prefer to do work on a different thread where it is
   * convenient. It is invoked exactly once on service shutdown, even when {@link #stopAsync} is
   * called multiple times.
   *
   * <p>If {@link #stopAsync} is called on a {@link State#STARTING} service, this method is not
   * invoked immediately. Instead, it will be deferred until after the service is {@link

          }
        });
  }

  /**
   * Invokes the subscriber method. This method can be overridden to make the invocation
   * synchronized.
   */
  @VisibleForTesting
  void invokeSubscriberMethod(Object event) throws InvocationTargetException {
    try {
      method.invoke(target, checkNotNull(event));
    } catch (IllegalArgumentException e) {

import java.util.logging.Level;

/**
 * A list of listeners for implementing a concurrency friendly observable object.
 *
 * <p>Listeners are registered once via {@link #addListener} and then may be invoked by {@linkplain
 * #enqueue enqueueing} and then {@linkplain #dispatch dispatching} events.
 *
 * <p>The API of this class is designed to make it easy to achieve the following properties
 *
 * <ul>

    /**
     * Invokes the method and returns its result.
     *
     * @param <T>
     *            the return type of the method
     * @param target
     *            the target object. Must not be {@literal null}
     * @param args
     *            the method arguments
     * @return the result of the method
     */
    <T> T invoke(Object target, Object... args);

    /**

                Arguments.of(-1, -2L, -3L, -4L, -5L) // negative values
        );
    }

    // --- Mockito interaction: verify each getter is invoked and returns stubbed values ---
    @Test
    void mockitoMock_verifiesGetterInteractions() {
        // Arrange: mock and stub each getter with distinct values

   *
   * <p>Cancellation does not propagate from the output future to a callable that has begun to
   * execute, but if the output future is cancelled before {@link Callable#call()} is invoked,
   * {@link Callable#call()} will not be invoked.
   */
  public <T extends @Nullable Object> ListenableFuture<T> submit(
      Callable<T> callable, Executor executor) {
    checkNotNull(callable);
    checkNotNull(executor);

    @Override
    protected @Nullable Object handleInvocation(
        Object p, Method calledMethod, @Nullable Object[] args) throws Throwable {
      assertEquals(method, calledMethod);
      assertEquals(method + " invoked more than once.", 0, called.get());
      for (int i = 0; i < passedArgs.length; i++) {
        assertEquals(
            "Parameter #" + i + " of " + method + " not forwarded", passedArgs[i], args[i]);
      }

   *
   * <p>Cancellation does not propagate from the output future to a callable that has begun to
   * execute, but if the output future is cancelled before {@link Callable#call()} is invoked,
   * {@link Callable#call()} will not be invoked.
   */
  public <T extends @Nullable Object> ListenableFuture<T> submit(
      Callable<T> callable, Executor executor) {
    checkNotNull(callable);
    checkNotNull(executor);

import java.util.logging.Level;

/**
 * A list of listeners for implementing a concurrency friendly observable object.
 *
 * <p>Listeners are registered once via {@link #addListener} and then may be invoked by {@linkplain
 * #enqueue enqueueing} and then {@linkplain #dispatch dispatching} events.
 *
 * <p>The API of this class is designed to make it easy to achieve the following properties
 *
 * <ul>

 * {@link FinalizableReference#finalizeReferent()} on them. Java 9+ users should prefer {@link
 * java.lang.ref.Cleaner Cleaner}; see example <a href="#cleaner">below</a>.
 *
 * <p>Keep a strong reference to this object until all of the associated referents have been
 * finalized. If this object is garbage collected earlier, the backing thread will not invoke {@code