*   <li>keys automatically wrapped in {@linkplain WeakReference weak} references
 *   <li>values automatically wrapped in {@linkplain WeakReference weak} or {@linkplain
 *       SoftReference soft} references
 *   <li>notification of evicted (or otherwise removed) entries
 *   <li>accumulation of cache access statistics
 * </ul>
 *
 * <p>These features are all optional; caches can be created using all or none of them. By default,

  // Element Mutation

  @Test
  public void addEdge_existingNodes() {
    assume().that(graphIsMutable()).isTrue();

    // Adding nodes initially for safety (insulating from possible future
    // modifications to proxy methods)
    addNode(N1);
    addNode(N2);
    assertThat(networkAsMutableNetwork.addEdge(N1, N2, E12)).isTrue();
    assertThat(network.edges()).contains(E12);

      notifyStarted();
    }

    @Override
    protected void doStop() {
      notifyStopped();
    }
  }

  /*
   * A NoOp service that will delay the startup and shutdown notification for a configurable amount
   * of time.
   */
  private static class NoOpDelayedService extends NoOpService {
    private final long delay;

    NoOpDelayedService(long delay) {
      this.delay = delay;
    }

   * elements.length) are all {@code null}.
   */
  @VisibleForTesting transient @Nullable Object @Nullable [] elements;

  /**
   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such

   * ConcurrentModificationException}, and guarantees to traverse elements as they existed upon
   * construction of the iterator, and may (but is not guaranteed to) reflect any modifications
   * subsequent to construction.
   *
   * @return an iterator over the elements in this queue in proper sequence
   */
  @CanIgnoreReturnValue
  @Override
  public Iterator<E> iterator() {

      notifyStarted();
    }

    @Override
    protected void doStop() {
      notifyStopped();
    }
  }

  /*
   * A NoOp service that will delay the startup and shutdown notification for a configurable amount
   * of time.
   */
  private static class NoOpDelayedService extends NoOpService {
    private final long delay;

    NoOpDelayedService(long delay) {
      this.delay = delay;
    }

    /** SMB2 query info command */
    protected static final short SMB2_QUERY_INFO = 0x0010;
    /** SMB2 set info command */
    protected static final short SMB2_SET_INFO = 0x0011;
    /** SMB2 opportunistic lock break notification */
    protected static final short SMB2_OPLOCK_BREAK = 0x0012;

    /**
     * Flag indicating the message is a response from server to client.
     */

   * will never throw {@link ConcurrentModificationException}, and guarantees to traverse elements
   * as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect
   * any modifications subsequent to construction.
   *
   * @return an iterator over the elements in this queue
   */
  @CanIgnoreReturnValue // pushed down from class to method
  @Override
  public Iterator<E> iterator() {

    public static final String LABELS_google_chat_webhook_urls = "{labels.google_chat_webhook_urls}";

    /** The key of the message: Log Notification */
    public static final String LABELS_log_notification_enabled = "{labels.log_notification_enabled}";

    /** The key of the message: Log Notification Level */
    public static final String LABELS_log_notification_level = "{labels.log_notification_level}";

    /* UnsupportedOperationException on direct modifications. */
    assertThrows(UnsupportedOperationException.class, () -> unmod.put(4, "four"));
    assertThrows(UnsupportedOperationException.class, () -> unmod.forcePut(4, "four"));
    assertThrows(UnsupportedOperationException.class, () -> unmod.putAll(singletonMap(4, "four")));

    /* UnsupportedOperationException on indirect modifications. */