Another odd thing with hibernate:

using the code below I'm unable to update entity data but successfully may add new one to collection :

/**
 * Writes qualification info into DB
 *
 * @param qualification object model to be updated
 * @return true if successfull
 * @throws Exception
 */
 public boolean saveQualification(UsersAcademicQualifications qualification) throws Exception {
 if (qualification != null) {

 usersAcademicQualificationsHome.setInstance(qualification);

 if (qualification.getId() != null && qualification.getId().trim().length() > 0) {
 usersAcademicQualificationsHome.update();
 }
 else {
 usersAcademicQualificationsHome.persist();
 }

 usersAcademicQualificationsHome.getEntityManager().flush();

 //updating related entities
 usersAcademicQualificationsHome.setId(qualification.getId());
 qualification = usersAcademicQualificationsHome.find();

 //adding new qualification to related Users object
 {
 qualification.getUsers().getUsersAcademicQualifications().add(qualification);
 usersFacade.saveUser(qualification.getUsers());
 }

 return true;
 }
 return false;
 }