*/
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSetMultimap<K, V>> flatteningToImmutableSetMultimap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
    return CollectCollectors.flatteningToImmutableSetMultimap(keyFunction, valuesFunction);
  }

  /**
   * Returns the empty multimap.
   *

  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSetMultimap<K, V>> flatteningToImmutableSetMultimap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
    return CollectCollectors.flatteningToImmutableSetMultimap(keyFunction, valuesFunction);
  }

  /**
   * Returns the empty multimap.
   *

        ImmutableSetMultimap.Builder::combine,
        ImmutableSetMultimap.Builder::build);
  }

  static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSetMultimap<K, V>> flatteningToImmutableSetMultimap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
    checkNotNull(keyFunction);
    checkNotNull(valuesFunction);