uniqueIndex(
          Iterables.<MapsImplEnum>concat(
              asList(MapImpl.values()), asList(SortedMapImpl.values()), asList(BiMapImpl.values())),
          toStringFunction());

  @Param({
    "HashMapImpl",
    "LinkedHashMapImpl",
    "ConcurrentHashMapImpl",
    "CompactHashMapImpl",
    "CompactLinkedHashMapImpl",
    "ImmutableMapImpl",
    "TreeMapImpl",
    "ImmutableSortedMapImpl",

      }
    };

    abstract <K extends Comparable<K>, V extends Comparable<V>> SetMultimap<K, V> create(
        Multimap<K, V> contents);
  }

  public enum MapImpl implements MapsImplEnum {
    HashMapImpl {
      @Override
      public <K extends Comparable<K>, V> Map<K, V> create(Map<K, V> map) {
        return new HashMap<>(map);
      }
    },
    LinkedHashMapImpl {
      @Override