result.removeAll(newCollection.getCollection());
List<BugInstance> inBoth = getSharedInstances(result, newCollection);   removeBugInstances(result, inBoth);
		public SortedBugCollection perform(Set<BugInstance> result,				SortedBugCollection origCollection, SortedBugCollection newCollection) {			result.addAll(origCollection.getCollection());			result.removeAll(newCollection.getCollection());			return origCollection;		}