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;
  }

        Map<K, V> map, Comparator<? super V> valueComparator) {
      Ordering<K> keyOrdering =
          new Ordering<K>() {
            @Override
            public int compare(K left, K right) {
              // requireNonNull is safe because we are passing keys in the map.
              return valueComparator.compare(
                  requireNonNull(map.get(left)), requireNonNull(map.get(right)));

    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 =

     */
    @CanIgnoreReturnValue
    @Override
    @Deprecated
    @DoNotCall("Always throws UnsupportedOperationException")
    public final Builder<K, V> orderEntriesByValue(Comparator<? super V> valueComparator) {
      throw new UnsupportedOperationException("Not available on ImmutableSortedMap.Builder");
    }

    /*
     * While the current implementation returns `this`, that's not something we mean to guarantee.

     */
    @CanIgnoreReturnValue
    @Override
    @Deprecated
    @DoNotCall("Always throws UnsupportedOperationException")
    public final Builder<K, V> orderEntriesByValue(Comparator<? super V> valueComparator) {
      throw new UnsupportedOperationException("Not available on ImmutableSortedMap.Builder");
    }

    /*
     * While the current implementation returns `this`, that's not something we mean to guarantee.