SampleElements<K> sampleKeys =
          ((TestMultimapGenerator<K, V, M>) multimapGenerator.getInnerGenerator()).sampleKeys();
      SampleElements<V> sampleValues =
          ((TestMultimapGenerator<K, V, M>) multimapGenerator.getInnerGenerator()).sampleValues();
      return new SampleElements<>(
          mapEntry(sampleKeys.e0(), createCollection(sampleValues.e0())),

   *       UnsupportedOperationException when those mutators
   * </ol>
   *
   * @param multimap the presumed-immutable multimap
   * @param sampleKey a key of the same type as that contained by {@code multimap}. {@code multimap}
   *     may or may not have {@code sampleKey} as a key.
   * @param sampleValue a key of the same type as that contained by {@code multimap}. {@code

  }

  public void testCombinations() {
    ImmutableList<Set<Integer>> sampleSets =
        ImmutableList.<Set<Integer>>of(
            ImmutableSet.<Integer>of(),
            ImmutableSet.of(1, 2),
            ImmutableSet.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
    for (Set<Integer> sampleSet : sampleSets) {
      for (int k = 0; k <= sampleSet.size(); k++) {
        int size = k;