Yes, support for different flavor of Collection classes in PojoCache has been in my mind for a while. TO fully address this, I have just created a jira and put my thought in there: http://jira.jboss.com/jira/browse/JBCACHE-893 Please check it out. Of course, as genman mentioned, if you want to your own flavor of SortedSet, you will probably need sorted node underneath for performance. As for the CCE, you can file a bug for future reference and a junit case will be nice as well. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3990771#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...