*
   * @since 16.0
   */
  public abstract static class SortedSetMultimapBuilder<
          K0 extends @Nullable Object, V0 extends @Nullable Object>
      extends SetMultimapBuilder<K0, V0> {
    SortedSetMultimapBuilder() {}

    @Override
    public abstract <K extends K0, V extends V0> SortedSetMultimap<K, V> build();

    @Override