Same as Aliaksei we "played" around with this issue and at the ended up in a complete project restart because jbpm5 was just too cumbersome to use and the issue discussed here took me days. Thanks to this posting we tried out activiti and after 3 weeks only our web application with activiti engine for bpm is running.
Sorry if anyone feels offended, but keeping things simple should be a must for such broadly used components. Today I cannot understand why I tried to edit all these xmls and tried to avoid the conflicts with different hibernate versions etc.
Hope it helps anyone to decide between jbpm 5 and activiti and maybe even people from jbpm may consider a next version, which really would be capable to run with a java ee web application. The current one only worked as a standalone java program