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

  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);

      return this;
    }

    @CanIgnoreReturnValue
    Builder<E> combine(Builder<E> other) {
      requireNonNull(impl);
      requireNonNull(other.impl);
      /*
       * For discussion of requireNonNull, see the comment on the field.
       *
       * (And I don't believe there's any situation in which we call x.combine(y) when x is a plain

  public void testToImmutableSetMultimap_java7_combine() {
    ImmutableSetMultimap.Builder<String, Integer> zis =
        ImmutableSetMultimap.<String, Integer>builder().put("a", 1).put("b", 2);
    ImmutableSetMultimap.Builder<String, Integer> zat =
        ImmutableSetMultimap.<String, Integer>builder().put("a", 3).put("c", 4);
    ImmutableSetMultimap<String, Integer> multimap = zis.combine(zat).build();

      super.putAll(multimap);
      return this;
    }

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

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

        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

            }
          }
        }
      }
    }
  }

  // TODO(b/172823566): Use mainline testToImmutableRangeSet once CollectorTester is usable to java7
  public void testToImmutableRangeSet_java7_combine() {
    Range<Integer> rangeOne = Range.closedOpen(1, 3);
    Range<Integer> rangeTwo = Range.closedOpen(7, 9);
    Range<Integer> rangeThree = Range.closedOpen(4, 5);
    Range<Integer> rangeFour = Range.closedOpen(6, 7);

    ImmutableSet.Builder<String> zis = ImmutableSet.<String>builder().add("a", "b", "a");
    ImmutableSet.Builder<String> zat = ImmutableSet.<String>builder().add("c", "b", "d", "c");
    ImmutableSet<String> set = zis.combine(zat).build();
    assertThat(set).containsExactly("a", "b", "c", "d").inOrder();
  }

  @Override
  <E extends Comparable<E>> Builder<E> builder() {
    return ImmutableSet.builder();
  }

  @Override

    checkNonnegative(k, "k");
    checkNotNull(comparator);
    return Collector.of(
        () -> TopKSelector.<T>least(k, comparator),
        TopKSelector::offer,
        TopKSelector::combine,
        TopKSelector::topK,
        Collector.Characteristics.UNORDERED);
  }

  /**
   * Returns a {@code Collector} that returns the {@code k} greatest (relative to the specified