In hibernate, the HQL query "from Entity1 join Entity2" will return List<Object[]> with Object[0] being Entity1 and Object[2] being Entity2.
You could use a custom BeanModel and PropertyConduits to look up properties from the Object[] array. See the demo here which uses a custom BeanModel and PropertyConduits to generate a grid from a List<Map> http://tapestry-stitch.uklance.cloudbees.net/mapgriddemo