* intersection of the two maps.
   */
  Map<K, V> entriesInCommon();

  /**
   * Returns an unmodifiable map describing keys that appear in both maps, but with different
   * values.
   */
  Map<K, ValueDifference<V>> entriesDiffering();

  /**
   * Compares the specified object with this instance for equality. Returns {@code true} if the
   * given object is also a {@code MapDifference} and the values returned by the {@link

   * intersection of the two maps.
   */
  Map<K, V> entriesInCommon();

  /**
   * Returns an unmodifiable map describing keys that appear in both maps, but with different
   * values.
   */
  Map<K, ValueDifference<V>> entriesDiffering();

  /**
   * Compares the specified object with this instance for equality. Returns {@code true} if the
   * given object is also a {@code MapDifference} and the values returned by the {@link

    @ParametricNullness
    public V rightValue() {
      return right;
    }

    @Override
    public boolean equals(@Nullable Object object) {
      if (object instanceof ValueDifference) {
        ValueDifference<?> that = (ValueDifference<?>) object;
        return Objects.equals(this.left, that.leftValue())
            && Objects.equals(this.right, that.rightValue());
      }
      return false;
    }

    @ParametricNullness
    public V rightValue() {
      return right;
    }

    @Override
    public boolean equals(@Nullable Object object) {
      if (object instanceof ValueDifference) {
        ValueDifference<?> that = (ValueDifference<?>) object;
        return Objects.equals(this.left, that.leftValue())
            && Objects.equals(this.right, that.rightValue());
      }
      return false;
    }