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 testToImmutableSortedMap_java7_combine() {
    ImmutableSortedMap.Builder<String, Integer> zis =
        ImmutableSortedMap.<String, Integer>naturalOrder().put("one", 1).put("four", 4);
    ImmutableSortedMap.Builder<String, Integer> zat =
        ImmutableSortedMap.<String, Integer>naturalOrder().put("two", 2).put("three", 3);
    ImmutableSortedMap<String, Integer> sortedMap = zis.combine(zat).build();

  public void testToImmutableMap_java7_combine() {
    ImmutableMap.Builder<String, Integer> zis =
        ImmutableMap.<String, Integer>builder().put("one", 1);
    ImmutableMap.Builder<String, Integer> zat =
        ImmutableMap.<String, Integer>builder().put("two", 2).put("three", 3);
    assertMapEquals(zis.combine(zat).build(), "one", 1, "two", 2, "three", 3);
  }

    @Override
    public Builder<E> addAll(Iterator<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    Builder<E> combine(Builder<E> builder) {
      super.combine(builder);
      return this;
    }

    @Override
    public ImmutableSortedSet<E> build() {
      return copyOfInternal(comparator, contents.iterator());
    }
  }

      for (Cell<? extends R, ? extends C, ? extends V> cell : table.cellSet()) {
        put(cell);
      }
      return this;
    }

    @CanIgnoreReturnValue
    Builder<R, C, V> combine(Builder<R, C, V> other) {
      this.cells.addAll(other.cells);
      return this;
    }

    /**
     * Returns a newly-created immutable table.
     *

            }
          }
        }
      }
    }
  }

  // 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);

        Callable<C> combiner, Executor executor) {
      return new CombinedFuture<>(futures, allMustSucceed, executor, combiner);
    }

    /**
     * Creates the {@link ListenableFuture} which will return the result of running {@code combiner}
     * when all Futures complete. {@code combiner} will run using {@code executor}.
     *

  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();

    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterator<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    Builder<E> combine(Builder<E> builder) {
      contents.addAll(builder.contents);
      return this;
    }

    @Override
    public ImmutableSet<E> build() {
      return copyOf(contents.iterator());
    }
  }

      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