String oneSizeName =
          Platform.format(
              "%s [collection size: %s]", name, collectionSize.toString().toLowerCase());
      OneSizeGenerator<T, E> oneSizeGenerator =
          new OneSizeGenerator<>(getSubjectGenerator(), (CollectionSize) collectionSize);
      Set<Feature<?>> oneSizeFeatures = copyToSet(features);
      oneSizeFeatures.add(collectionSize);

      }

      return mapGenerator.create(entries.toArray()).keySet();
    }

    @Override
    public K[] createArray(int length) {
      // TODO: with appropriate refactoring of OneSizeGenerator, we can perhaps
      // tidy this up and get rid of the casts here and in
      // MapValueCollectionGenerator.

      return ((TestMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createKeyArray(length);