@Override
    public boolean containsAll(Collection<?> collection) {
      if (collection instanceof SingletonImmutableOrdinalSet) {
        return element.equals(((SingletonImmutableOrdinalSet<?>) collection).element);
      }
      return super.containsAll(collection);
    }
Will throw an exception and leave the collection unmodified.
@throws UnsupportedOperationException always
@deprecated Modification operation are not supported.
ordinal/src/org/immutables/ordinal/ImmutableOrdinalSet.java