We need to be able to sort results by attribute value. I think an API like this could work:

List<PObject> users = repository.createFilter("User")
   .like("name", "a%")
   .orderBy("name")
   .list();

Maybe a better API would be sortAsc and sortDesc. The following example would sort first by release date, newest first, then by title, alphabetically:

List<PObject> objects = repository.createFilter("Songs")
  .in("tags", "rock")
  .sortDesc("releaseDate")
  .sortAsc("title")
  .list();

Since we are using the Criteria API from Hibernate under the hood, we can transfer the same semantics.