private DigitalObjectDocument.DigitalObject createDigitalObject(DigitalObjectDocument dof) {
   DigitalObjectDocument.DigitalObject dobj = dof.addNewDigitalObject();
   dobj.setVERSION(DigitalObjectType.VERSION.X_1_1);
   if (pid != null) {
     dobj.setPID(pid);
   }
   return dobj;
 }