private Set<Pair<Boolean, String>> collectDuplicates() {
      Set<Pair<Boolean, String>> result = new HashSet<>();

      for (Change change : myDetailedList) {
        addDuplicate(result, true, change.getBeforeRevision());
        addDuplicate(result, false, change.getAfterRevision());
      }

      return result;
    }
private Set<Pair<Boolean, String>> collectDuplicates()