*   networkService.send(packet);
 * }
 * }</pre>
 *
 * <p>It is important to note that the number of permits requested <i>never</i> affects the
 * throttling of the request itself (an invocation to {@code acquire(1)} and an invocation to {@code
 * acquire(1000)} will result in exactly the same throttling, if any), but it affects the throttling
 * of the <i>next</i> request. I.e., if an expensive task arrives at an idle RateLimiter, it will be

  protected AbstractService() {}

  /**
   * This method is called by {@link #startAsync} to initiate service startup. The invocation of
   * this method should cause a call to {@link #notifyStarted()}, either during this method's run,
   * or after it has returned. If startup fails, the invocation should cause a call to {@link
   * #notifyFailed(Throwable)} instead.
   *

   * fallback}. {@link Function#apply} is not invoked until the primary input has failed, so if the
   * primary input succeeds, it is never invoked. If, during the invocation of {@code fallback}, an
   * exception is thrown, this exception is used as the result of the output {@code Future}.
   *
   * <p>Usage example:
   *
   * <pre>{@code

 *   <li>No stats are modified by operations invoked on the {@linkplain Cache#asMap asMap} view of
 *       the cache.
 * </ul>
 *
 * <p>A lookup is specifically defined as an invocation of one of the methods {@link
 * LoadingCache#get(Object)}, {@link LoadingCache#getUnchecked(Object)}, {@link Cache#get(Object,
 * Callable)}, or {@link LoadingCache#getAll(Iterable)}.
 *
 * @author Charles Fry

 *   <li>No stats are modified by operations invoked on the {@linkplain Cache#asMap asMap} view of
 *       the cache.
 * </ul>
 *
 * <p>A lookup is specifically defined as an invocation of one of the methods {@link
 * LoadingCache#get(Object)}, {@link LoadingCache#getUnchecked(Object)}, {@link Cache#get(Object,
 * Callable)}, or {@link LoadingCache#getAll(Iterable)}.
 *
 * @author Charles Fry

            return ref.get() == null;
          }
        });
  }

  /**
   * Tries to perform a "full" garbage collection cycle (including processing of weak references and
   * invocation of finalize methods) and waits for it to complete. Ensures that at least one weak
   * reference has been cleared and one {@code finalize} method has been run before this method

    TypeVariable<D> typeVariable =
        Reflection.newProxy(
            TypeVariable.class, new TypeVariableInvocationHandler(typeVariableImpl));
    return typeVariable;
  }

  /**
   * Invocation handler to work around a compatibility problem between Java 7 and Java 8.
   *
   * <p>Java 8 introduced a new method {@code getAnnotatedBounds()} in the {@link TypeVariable}

   * throwing exceptions like {@link NoSuchElementException} at the appropriate times, it throws
   * {@link PermittedMetaException} instances, which wrap a set of all exceptions that the iterator
   * could throw during the invocation of that method. This is necessary because, e.g., a call to
   * {@code iterator().remove()} of an unmodifiable list could throw either {@link
   * IllegalStateException} or {@link UnsupportedOperationException}. Note that iterator

            return ref.get() == null;
          }
        });
  }

  /**
   * Tries to perform a "full" garbage collection cycle (including processing of weak references and
   * invocation of finalize methods) and waits for it to complete. Ensures that at least one weak
   * reference has been cleared and one {@code finalize} method has been run before this method

   * throwing exceptions like {@link NoSuchElementException} at the appropriate times, it throws
   * {@link PermittedMetaException} instances, which wrap a set of all exceptions that the iterator
   * could throw during the invocation of that method. This is necessary because, e.g., a call to
   * {@code iterator().remove()} of an unmodifiable list could throw either {@link
   * IllegalStateException} or {@link UnsupportedOperationException}. Note that iterator