Currently on DistinctExitOperation, I do see that we have apply implementation, but this has been marked as UnsupportedOperationException on constructor, I don't understand why is that, may I know why?

Set<Object> uniqueSet = Sets.newHashSet();
uniqueSet.addAll(ExitOperationUtils.getNonNullList(results));
List<Object> uniqueList = Lists.newArrayList(uniqueSet);
return uniqueList;