java find duplicate element in list

1	public static Set<String> findDuplicates(List<String> listContainingDuplicates) {
2 
3		final Set<String> setToReturn = new HashSet<String>();
4		final Set<String> set1 = new HashSet<String>();
5 
6		for (String yourInt : listContainingDuplicates) {
7			if (!set1.add(yourInt)) {
8				setToReturn.add(yourInt);
9			}
10		}
11		return setToReturn;
12	}