*
     * @throws IllegalArgumentException if {@code expectedValuesPerKey < 0}
     */
    public SetMultimapBuilder<K0, @Nullable Object> hashSetValues(int expectedValuesPerKey) {
      checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
      return new SetMultimapBuilder<K0, @Nullable Object>() {
        @Override
        public <K extends K0, V extends @Nullable Object> SetMultimap<K, V> build() {

  private static <K extends @Nullable Object>
      SortedSetMultimapBuilder<K, Comparable<?>> rawtypeToWildcard(
          SortedSetMultimapBuilder<K, Comparable> setMultimapBuilder) {
    return (SortedSetMultimapBuilder) setMultimapBuilder;
  }

  @GwtIncompatible
  @J2ktIncompatible
    public void testSerialization() throws Exception {
    for (MultimapBuilderWithKeys<?> builderWithKeys :