}
      return orderedValues;
    }
  }

  private static final class KeysGenerator<K, V, M extends Multimap<K, V>>
      implements TestMultisetGenerator<K>, DerivedGenerator {
    private final OneSizeTestContainerGenerator<M, Entry<K, V>> multimapGenerator;

    public KeysGenerator(OneSizeTestContainerGenerator<M, Entry<K, V>> multimapGenerator) {
      this.multimapGenerator = multimapGenerator;