public OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> getInnerGenerator() {
      return mapGenerator;
    }
  }

  // TODO: investigate some API changes to SampleElements that would tidy up
  // parts of the following classes.

  static <K extends @Nullable Object, V extends @Nullable Object>
      TestSetGenerator<K> keySetGenerator(
          OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {

    public OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> getInnerGenerator() {
      return mapGenerator;
    }
  }

  // TODO: investigate some API changes to SampleElements that would tidy up
  // parts of the following classes.

  static <K extends @Nullable Object, V extends @Nullable Object>
      TestSetGenerator<K> keySetGenerator(
          OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {