* @since 19.0
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> orderEntriesByValue(Comparator<? super V> valueComparator) {
      super.orderEntriesByValue(valueComparator);
      return this;
    }

    @Override
    @CanIgnoreReturnValue
    Builder<K, V> combine(ImmutableMap.Builder<K, V> builder) {
      super.combine(builder);

     *
     * @since 8.0
     */
    @CanIgnoreReturnValue
    public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
      this.valueComparator = checkNotNull(valueComparator);
      return this;
    }

    @CanIgnoreReturnValue
    Builder<K, V> combine(Builder<K, V> other) {
      if (other.builderMap != null) {

  Map<K, Collection<V>> asMap();

  /**
   * Returns the comparator that orders the multimap values, with {@code null} indicating that
   * natural ordering is used.
   */
  @Nullable Comparator<? super V> valueComparator();

    transient Supplier<? extends SortedSet<V>> factory;
    transient @Nullable Comparator<? super V> valueComparator;

    CustomSortedSetMultimap(Map<K, Collection<V>> map, Supplier<? extends SortedSet<V>> factory) {
      super(map);
      this.factory = checkNotNull(factory);
      valueComparator = factory.get().comparator();
    }

    @Override
    Set<K> createKeySet() {

    transient Supplier<? extends SortedSet<V>> factory;
    transient @Nullable Comparator<? super V> valueComparator;

    CustomSortedSetMultimap(Map<K, Collection<V>> map, Supplier<? extends SortedSet<V>> factory) {
      super(map);
      this.factory = checkNotNull(factory);
      valueComparator = factory.get().comparator();
    }

    @Override
    Set<K> createKeySet() {

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

    @Override
    public Builder<K, V> orderEntriesByValue(Comparator<? super V> valueComparator) {
      throw new UnsupportedOperationException("Not available on ImmutableSortedMap.Builder");
    }

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

    assertThat(copy.keySet()).containsExactly("foo", "google", "tree").inOrder();
    assertEquals(multimap.keyComparator(), copy.keyComparator());
    assertEquals(multimap.valueComparator(), copy.valueComparator());
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testTreeMultimapDerived() {

    assertThat(copy.keySet()).containsExactly("foo", "google", "tree").inOrder();
    assertEquals(multimap.keyComparator(), copy.keyComparator());
    assertEquals(multimap.valueComparator(), copy.valueComparator());
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testTreeMultimapDerived() {

    assertThat(copy.keySet()).containsExactly(null, "tree", "google").inOrder();
    assertEquals(multimap.keyComparator(), copy.keyComparator());
    assertEquals(multimap.valueComparator(), copy.valueComparator());
  }

        return delegate().replaceValues(key, values); // copy not synchronized
      }
    }

    @Override
    public @Nullable Comparator<? super V> valueComparator() {
      synchronized (mutex) {
        return delegate().valueComparator();
      }
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }