* iterator} method of {@link #entrySet}. If you override {@link #entrySet}, you may wish to
   * 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