* override {@link #containsKey} to forward to this implementation.
   *
   * @since 7.0
   */
  protected boolean standardContainsKey(@Nullable Object key) {
    return Maps.containsKeyImpl(this, key);
  }

  /**
   * A sensible implementation of {@link Map#values} in terms of the following methods: {@link
   * ForwardingMap#clear}, {@link ForwardingMap#containsValue}, {@link ForwardingMap#isEmpty},