entry.setValueReference(valueRef);
    return entry;
  }

  static class DummyEntry<K, V> implements ReferenceEntry<K, V> {
    private @Nullable K key;
    private final int hash;
    private final ReferenceEntry<K, V> next;

    public DummyEntry(K key, int hash, ReferenceEntry<K, V> next) {
      this.key = key;
      this.hash = hash;
      this.next = next;
    }

    entry.setValueReference(valueRef);
    return entry;
  }

  static class DummyEntry<K, V> implements ReferenceEntry<K, V> {
    private @Nullable K key;
    private final int hash;
    private final ReferenceEntry<K, V> next;

    public DummyEntry(K key, int hash, ReferenceEntry<K, V> next) {
      this.key = key;
      this.hash = hash;
      this.next = next;
    }

          @ParametricNullness V5 value5)
          throws Exception;
    }

    private final ClosingFuture<V1> future1;
    private final ClosingFuture<V2> future2;
    private final ClosingFuture<V3> future3;
    private final ClosingFuture<V4> future4;
    private final ClosingFuture<V5> future5;

    private Combiner5(
        ClosingFuture<V1> future1,
        ClosingFuture<V2> future2,

      implements MapDifference.ValueDifference<V> {
    @ParametricNullness private final V left;
    @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) {