}
      return this;
    }

    @CanIgnoreReturnValue
    public Builder<K, V> orderEntriesByValue(Comparator<? super V> valueComparator) {
      checkState(this.valueComparator == null, "valueComparator was already set");
      this.valueComparator = checkNotNull(valueComparator, "valueComparator");
      return this;
    }

    @CanIgnoreReturnValue
    Builder<K, V> combine(Builder<K, V> other) {

    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());
  }

    SortedSetMultimap<String, Integer> multimap = synchronizedSortedSetMultimap(delegate);
    checkUnmodifiableMultimap(multimap, false, "null", 42);
    assertThat(multimap.valueComparator()).isEqualTo(INT_COMPARATOR);
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testSerializingUnmodifiableSynchronizedTreeMultimap() {
    TreeMultimap<String, Integer> delegate =