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);

    assertEquals(ImmutableSetMultimap.of(1, "one"), ImmutableSetMultimap.of("one", 1).inverse());
    assertEquals(
        ImmutableSetMultimap.of(1, "one", 2, "two"),
        ImmutableSetMultimap.of("one", 1, "two", 2).inverse());
    assertEquals(
        ImmutableSetMultimap.of('o', "of", 'f', "of", 't', "to", 'o', "to"),
        ImmutableSetMultimap.of("of", 'o', "of", 'f', "to", 't', "to", 'o').inverse());
  }

                  @Override
                  SetMultimap<String, Integer> filter(SetMultimap<String, Integer> multimap) {
                    ImmutableSetMultimap<String, Integer> badEntries =
                        ImmutableSetMultimap.of("foo", 314, "one", 159, "two", 265, "bar", 358);
                    multimap.putAll(badEntries);
                    return Multimaps.filterEntries(

        }
      } finally {
        monitor.leave();
      }
    }

    ImmutableSetMultimap<State, Service> servicesByState() {
      ImmutableSetMultimap.Builder<State, Service> builder = ImmutableSetMultimap.builder();
      monitor.enter();
      try {
        for (Entry<State, Service> entry : servicesByState.entries()) {

        }
      } finally {
        monitor.leave();
      }
    }

    ImmutableSetMultimap<State, Service> servicesByState() {
      ImmutableSetMultimap.Builder<State, Service> builder = ImmutableSetMultimap.builder();
      monitor.enter();
      try {
        for (Entry<State, Service> entry : servicesByState.entries()) {

          .put(ListMultimap.class, ImmutableListMultimap.of())
          .put(ImmutableListMultimap.class, ImmutableListMultimap.of())
          .put(SetMultimap.class, ImmutableSetMultimap.of())
          .put(ImmutableSetMultimap.class, ImmutableSetMultimap.of())
          .put(
              SortedSetMultimap.class,
              Multimaps.unmodifiableSortedSetMultimap(TreeMultimap.create()))

                  @Override
                  SetMultimap<String, Integer> filter(SetMultimap<String, Integer> multimap) {
                    ImmutableSetMultimap<String, Integer> badEntries =
                        ImmutableSetMultimap.of("foo", 314, "one", 159, "two", 265, "bar", 358);
                    multimap.putAll(badEntries);
                    return Multimaps.filterEntries(

          .put(ListMultimap.class, ImmutableListMultimap.of())
          .put(ImmutableListMultimap.class, ImmutableListMultimap.of())
          .put(SetMultimap.class, ImmutableSetMultimap.of())
          .put(ImmutableSetMultimap.class, ImmutableSetMultimap.of())
          .put(
              SortedSetMultimap.class,
              Multimaps.unmodifiableSortedSetMultimap(TreeMultimap.create()))

import java.util.Collection;

/**
 * Implementation of {@link ImmutableListMultimap} with no entries.
 *
 * @author Mike Ward
 */
@GwtCompatible
final class EmptyImmutableSetMultimap extends ImmutableSetMultimap<Object, Object> {
  static final EmptyImmutableSetMultimap INSTANCE = new EmptyImmutableSetMultimap();

  private EmptyImmutableSetMultimap() {
    super(ImmutableMap.of(), 0, null);
  }

  /*

    ImmutableSetMultimap<String, Integer> expected =
        ImmutableSetMultimap.of("one", 1, "won", 1, "two", 2, "too", 2, "three", 3);
    assertEquals(expected, map.asMultimap());
  }

  public void testAsMultimapWhenEmpty() {
    ImmutableMap<String, Integer> map = ImmutableMap.of();
    ImmutableSetMultimap<String, Integer> expected = ImmutableSetMultimap.of();