final int weight;

    WeightedWeakValueReference(
        ReferenceQueue<V> queue, V referent, ReferenceEntry<K, V> entry, int weight) {
      super(queue, referent, entry);
      this.weight = weight;
    }

    @Override
    public int getWeight() {
      return weight;
    }

    @Override
    public ValueReference<K, V> copyFor(

    @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

    final int weight;

    WeightedWeakValueReference(
        ReferenceQueue<V> queue, V referent, ReferenceEntry<K, V> entry, int weight) {
      super(queue, referent, entry);
      this.weight = weight;
    }

    @Override
    public int getWeight() {
      return weight;
    }

    @Override
    public ValueReference<K, V> copyFor(