} else if (map instanceof SortedMap) {
      return new SortedAsMap((SortedMap<K, Collection<V>>) map);
    } else {
      return new AsMap(map);
    }
  }

  @WeakOuter
  private class AsMap extends ViewCachingAbstractMap<K, Collection<V>> {
    /**
     * Usually the same as map, but smaller for the headMap(), tailMap(), or subMap() of a
     * SortedAsMap.
     */