&& ((TestSortedMapGenerator<K, V>) generator).create().keySet() instanceof SortedSet) {
      return new MapSortedKeySetGenerator<>(mapGenerator);
    } else {
      return new MapKeySetGenerator<>(mapGenerator);
    }
  }

  public static class MapKeySetGenerator<K extends @Nullable Object, V extends @Nullable Object>
      implements TestSetGenerator<K>, DerivedGenerator {