I upgraded my ear from 5.2.0 to 5.3.0. It seems to work fine but persistence fails. An example what I mean:
I have a global handler who goes in all workitems. In this handler I save text or pictures generated by the workitems.
GuiProcessHandler handler = new GuiProcessHandler();
// add any text example
handler.addText(123124124l, "Hello World");
Map<String, Object> params = new HashMap<String, Object>();
// start a new process instance
ksession.startProcess(process_bpmn_id, params); //workitems make changes to the handler