return SetTestSuiteBuilder.using(entrySetGenerator);
  }

  protected SetTestSuiteBuilder<K> createDerivedKeySetSuite(TestSetGenerator<K> keySetGenerator) {
    return SetTestSuiteBuilder.using(keySetGenerator);
  }

  protected CollectionTestSuiteBuilder<V> createDerivedValueCollectionSuite(
      TestCollectionGenerator<V> valueCollectionGenerator) {

    }

    return derivedSuites;
  }

  @Override
  protected NavigableSetTestSuiteBuilder<K> createDerivedKeySetSuite(
      TestSetGenerator<K> keySetGenerator) {
    return NavigableSetTestSuiteBuilder.using((TestSortedSetGenerator<K>) keySetGenerator);
  }

  public static final class NavigableMapSubmapTestMapGenerator<K, V>
      extends SortedMapSubmapTestMapGenerator<K, V> {

    }

    return derivedSuites;
  }

  @Override
  protected NavigableSetTestSuiteBuilder<K> createDerivedKeySetSuite(
      TestSetGenerator<K> keySetGenerator) {
    return NavigableSetTestSuiteBuilder.using((TestSortedSetGenerator<K>) keySetGenerator);
  }

  public static final class NavigableMapSubmapTestMapGenerator<K, V>
      extends SortedMapSubmapTestMapGenerator<K, V> {

  }

  // 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) {
    TestContainerGenerator<Map<K, V>, Entry<K, V>> generator = mapGenerator.getInnerGenerator();
    if (generator instanceof TestSortedMapGenerator