Yes, those examples you are referring to are still using the legacy .rf format, and will not be supported in jBPM5. The tests are still there as they test the persistence behaviour and haven't been upgraded to BPMN2 yet. We will be updating drools with the latest jBPM5 runtime as well, so then you will probably be able to open those examples as well, but for now I suggest you stick to the examples in the BPMN2 project:
https://github.com/krisv/jbpm/tree/master/jbpm-bpmn2/src/test/resources
Kris