TreeSet<BugInstance> result = new TreeSet<BugInstance>(VersionInsensitiveBugComparator.instance());  operation.perform(result, origCollection, newCollection);
TreeSet<BugInstance> result = new TreeSet<BugInstance>(getComparator());
	public SortedBugCollection performSetOperation(SetOperation operation) {		TreeSet<BugInstance> result = new TreeSet<BugInstance>(VersionInsensitiveBugComparator.instance());		operation.perform(result, origCollection, newCollection);				SortedBugCollection resultCollection = new SortedBugCollection();		resultCollection.addAll(result);				return resultCollection;	}