class SetUtil {

	public static <S, T extends S, U extends S> boolean differenceEmpty(final Collection<T> a, final Collection<U> b) {
		if (a == null || a.isEmpty()) {
			return true;
		}
		for (S item : a) {
			if (!b.contains(item)) {
				return false;
			}
		}
		return true;
	}

	private  SetUtil();

}