List<StarredChange.Key> remove = new ArrayList<StarredChange.Key>();
if (req.getAddSet() != null) {
for (final Change.Id id : req.getAddSet()) {
if (!existing.contains(id)) {
add.add(new StarredChange(new StarredChange.Key(me, id)));
}
}
}
if (req.getRemoveSet() != null) {