[rules-users] Droos Guvnor 5.1.1 - Relation between Category and Package

Hi, I am using ServiceImplementaion.java class to read categories and packages in repository, I didn't find any method in this class to get like what all packages are there for Category. Can someone please point out me how to get this relation. We are developing small ui, where we show Category in dropdown, its packages in one more dropdown and rules in one more dropdown. This is little urgent requirement, help would be highly appreciated. Thanks Kumar