If a usertask has a default sequence flow, afterany modification the xml converter works wrong. It writes the usertask's 'default' attribute twice.
I attached a simple model (usetask1.bpmn): a usertask, 2 endevents, 2 sequence flows. The usertask's default flow is flow1. I modified some of the elements position, then saved again. The result: the usertask node has two 'default' attribute. When you try read this model, it will throw Exception
Eclipse Version: 4.3.1