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

  @GwtIncompatible // unreasonably slow
  public void testAsSetIteration() {
    Set<Entry<String, Collection<Integer>>> set =
        new LinkedHashSet<>(
            asList(
                immutableEntry("foo", (Collection<Integer>) asList(2, 3, 6)),