return mapGenerator;
    }
  }

  public static class MapSortedKeySetGenerator<
          K extends @Nullable Object, V extends @Nullable Object>
      extends MapKeySetGenerator<K, V> implements TestSortedSetGenerator<K>, DerivedGenerator {
    private final TestSortedMapGenerator<K, V> delegate;

    public MapSortedKeySetGenerator(
        OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {