ImmutableList.Builder::add,
          ImmutableList.Builder::combine,
          ImmutableList.Builder::build);

  private static final Collector<Object, ?, ImmutableSet<Object>> TO_IMMUTABLE_SET =
      Collector.of(
          ImmutableSet::builder,
          ImmutableSet.Builder::add,
          ImmutableSet.Builder::combine,
          ImmutableSet.Builder::build);

  @GwtIncompatible

          ImmutableList.Builder::add,
          ImmutableList.Builder::combine,
          ImmutableList.Builder::build);

  private static final Collector<Object, ?, ImmutableSet<Object>> TO_IMMUTABLE_SET =
      Collector.of(
          ImmutableSet::builder,
          ImmutableSet.Builder::add,
          ImmutableSet.Builder::combine,
          ImmutableSet.Builder::build);

  @GwtIncompatible

    List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      set(combine(localValues));
    }
  }

  @Override
  void releaseResources(ReleaseResourcesReason reason) {
    super.releaseResources(reason);
    this.values = null;
  }

  abstract C combine(List<@Nullable Present<V>> values);

  /** Used for {@link Futures#allAsList} and {@link Futures#successfulAsList}. */

    String SELF_COMBINATION_MODE_ATTRIBUTE = "combine.self";

    String SELF_COMBINATION_OVERRIDE = "override";

    String SELF_COMBINATION_MERGE = "merge";

    String SELF_COMBINATION_REMOVE = "remove";

    /**
     * In case of complex XML structures, combining can be done based on id.
     */
    String ID_COMBINATION_MODE_ATTRIBUTE = "combine.id";

    /**

        (Supplier<ImmutableTable.Builder<R, C, V>>) ImmutableTable.Builder::new,
        (builder, t) ->
            builder.put(rowFunction.apply(t), columnFunction.apply(t), valueFunction.apply(t)),
        ImmutableTable.Builder::combine,
        ImmutableTable.Builder::build);
  }

  static <T extends @Nullable Object, R, C, V>
      Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
          Function<? super T, ? extends R> rowFunction,

   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          ToOptionalState::new,
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.
   *

  }

  /**
   * A generic {@link Combiner} that lets you use a lambda or method reference to combine two {@link
   * ClosingFuture}s. Use {@link #whenAllSucceed(ClosingFuture, ClosingFuture)} to start this
   * combination.
   *
   * @param <V1> the type returned by the first future
   * @param <V2> the type returned by the second future
   */

      super.orderEntriesByValue(valueComparator);
      return this;
    }

    @CanIgnoreReturnValue
    Builder<K, V> combine(Builder<K, V> other) {
      super.combine(other);
      return this;
    }

    @Override
    public ImmutableBiMap<K, V> build() {
      return buildOrThrow();
    }

    @Override

  public void testToImmutableBiMap_java7_combine() {
    ImmutableBiMap.Builder<String, Integer> zis =
        ImmutableBiMap.<String, Integer>builder().put("one", 1);
    ImmutableBiMap.Builder<String, Integer> zat =
        ImmutableBiMap.<String, Integer>builder().put("two", 2).put("three", 3);
    ImmutableBiMap<String, Integer> biMap = zis.combine(zat).build();
    assertMapEquals(biMap, "one", 1, "two", 2, "three", 3);

        putAll(entry.getKey(), entry.getValue());
      }
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    Builder<K, V> combine(ImmutableMultimap.Builder<K, V> other) {
      super.combine(other);
      return this;
    }

    /**
     * {@inheritDoc}
     *
     * @since 8.0
     */
    @CanIgnoreReturnValue
    @Override