return ((TestMultimapGenerator<K, V, M>) multimapGenerator.getInnerGenerator())
          .createValueArray(length);
    }

    @Override
    public SampleElements<K> sampleKeys() {
      return ((TestMultimapGenerator<K, V, M>) multimapGenerator.getInnerGenerator()).sampleKeys();
    }

    @Override
    public SampleElements<V> sampleValues() {