protected void verify(List<String> elements) {
        assertEquals(elements, new ArrayList<>(multimap.keys()));
      }
    }.test();
  }

  @GwtIncompatible // unreasonably slow
  public void testValuesIteration() {
    new IteratorTester<Integer>(
        6, MODIFIABLE, newArrayList(2, 3, 4, 5, 6), IteratorTester.KnownOrder.KNOWN_ORDER) {
      private @Nullable SetMultimap<String, Integer> multimap;

      @Override