private final Deque<E> delegate = new LinkedList<>();
    private final Object mutex = new Object[0]; // something Serializable

    @Override
    public boolean offer(E o) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offer(o);
    }

    @Override
    public @Nullable E poll() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.poll();
    }

    @Override

  /** Constructor for use by subclasses. */
  protected ForwardingNavigableSet() {}

  @Override
  protected abstract NavigableSet<E> delegate();

  @Override
  public @Nullable E lower(@ParametricNullness E e) {
    return delegate().lower(e);
  }

  /**
   * A sensible definition of {@link #lower} in terms of the {@code descendingIterator} method of

    val delegate = delegate
    if (delegate != null) {
      this.delegate = null
      delegate.onOpen(webSocket, response)
    } else {
      events.add(Open(webSocket, response))
    }
  }

  override fun onMessage(
    webSocket: WebSocket,
    bytes: ByteString,
  ) {
    Platform.get().log("[WS $name] onMessage", Platform.INFO, null)
    val delegate = delegate
    if (delegate != null) {

      super(ForwardingSortedMultiset.this);
    }
  }

  @Override
  public Comparator<? super E> comparator() {
    return delegate().comparator();
  }

  @Override
  public SortedMultiset<E> descendingMultiset() {
    return delegate().descendingMultiset();
  }

  /**
   * A skeleton implementation of a descending multiset view. Normally, {@link

      implements Supplier<T>, Serializable {
    final Supplier<T> delegate;

    ThreadSafeSupplier(Supplier<T> delegate) {
      this.delegate = checkNotNull(delegate);
    }

    @Override
    @ParametricNullness
    public T get() {
      synchronized (delegate) {
        return delegate.get();
      }
    }

    @Override
    public String toString() {

  }

  private SafeTreeMap(NavigableMap<K, V> delegate) {
    this.delegate = checkNotNull(delegate);
    for (K k : keySet()) {
      checkValid(k);
    }
  }

  @Override
  public @Nullable Entry<K, V> ceilingEntry(K key) {
    return delegate.ceilingEntry(checkValid(key));
  }

  @Override
  public @Nullable K ceilingKey(K key) {
    return delegate.ceilingKey(checkValid(key));
  }

  @Override

        processor.completed("rootId", rootCompleteEvent)

        then:
        1 * delegate.started(rootDescriptor, rootTestStartEvent)
        1 * delegate.started(testDescriptor1, testStartEvent1)
        1 * delegate.started(testDescriptor2, testStartEvent2)
        1 * delegate.failure("testId2", testError2)
        0 * delegate.completed("rootId", rootCompleteEvent)

        when:

      return delegate.equals(o);
    }

    @Override
    public int hashCode() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.hashCode();
    }

    @Override
    public int size() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.size();
    }

    @Override
    public boolean isEmpty() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.isEmpty();
    }

   */
  private final transient EnumSet<E> delegate;

  private ImmutableEnumSet(EnumSet<E> delegate) {
    this.delegate = delegate;
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return Iterators.unmodifiableIterator(delegate.iterator());
  }

  @Override
  public Spliterator<E> spliterator() {

      implements Supplier<T>, Serializable {
    final Supplier<T> delegate;

    ThreadSafeSupplier(Supplier<T> delegate) {
      this.delegate = checkNotNull(delegate);
    }

    @Override
    @ParametricNullness
    public T get() {
      synchronized (delegate) {
        return delegate.get();
      }
    }

    @Override
    public String toString() {