我找到了答案:

("select d.key from Deliverable as d, Task as t
                where t.deliverable.id = d.id and
                t.id = (select max(t1.id) from Task t1 where t1.deliverable.id = d.id)
                and d.project.id= :id
                and t.user.username = :name
                order by t.id desc")
        .setMaxResults(3)
        .setLong("id", projectId)
        .setString("name", username)
        .list();