Actually Tihomir I wanted to prepare for the future. I hope flows defined in BPMN2 will replace rule-flows, so I was thinking about integration projects where you edit rules java code and processes in the same IDE.
For the moment I thought that editing manually the files would have allowed to compensate for what still is not implemented.
But actually I didn't understand whethe I got the error message because the xml is wrong or because I have the wrong jars in the classpath or other reasons.