I need modify the jBPM source code to use my own hibernate session (i.e. not using jBPM Hibernate configuration). I modified the HibernateHelper on db.hibernate package, DbPersistenceService and DbPersistenceServiceFactory class in persistence package. Do you know if I need modify other class?
You don't have to modify jBPM to use your own hibernate session and are not encorauged to do so, unless you intend to contribute it back :-)
Call JbpmContext.setSession(Session) and jBPM will use your session instead of creating one internally.