checkUnmodifiableMultimap(HashMultimap.<@Nullable String, @Nullable Integer>create(), false);
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testSerializingUnmodifiableHashMultimap() {
    Multimap<String, Integer> unmodifiable =
        prepareUnmodifiableTests(HashMultimap.<String, Integer>create(), false, null, null);
    SerializableTester.reserializeAndAssert(unmodifiable);
  }