Hi, The "problem" comes from the following code: | private Collection<Role> roles = new ArrayList<Role>(); | private Collection<Group> groups = new ArrayList<Group>(); | A Collection is treated as a "bag". You have have some possibilities to fix it. An easy solution is to use the @CollectionID. Another solution would be to change them to List<> and then use the @IndexColum, and the final solution is to change the to Set<>. You must read up on Hibernate Collection mapping first, to see whats suits your data model best. Go to this URL: http://www.hibernate.org/hib_docs/annotations/reference/en/html/entity.ht... Cheers, Andy View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4045401#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...