@ParametricNullness private final V right;

    static <V extends @Nullable Object> ValueDifference<V> create(
        @ParametricNullness V left, @ParametricNullness V right) {
      return new ValueDifferenceImpl<>(left, right);
    }

    private ValueDifferenceImpl(@ParametricNullness V left, @ParametricNullness V right) {
      this.left = left;
      this.right = right;
    }

    @Override