fail();
    } catch (NullPointerException expected) {
    }
  }

  // TODO(b/172823566): Use mainline testToImmutableListMultimap once CollectorTester is usable.
  public void testToImmutableListMultimap_java7_combine() {
    ImmutableListMultimap.Builder<String, Integer> zis =
        ImmutableListMultimap.<String, Integer>builder().put("a", 1).put("b", 2);
    ImmutableListMultimap.Builder<String, Integer> zat =