return derivedFeatures;
  }

  private static final class AsMapGenerator<K, V, M extends Multimap<K, V>>
      implements TestMapGenerator<K, Collection<V>>, DerivedGenerator {
    private final OneSizeTestContainerGenerator<M, Entry<K, V>> multimapGenerator;

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