@Override
 public void toHitsModel(TimeTableCellType source, TimeTableSubject target) {
   if (source != null && target != null) {
     target.setRefId(source.getTimeTableSubjectRefId());
     target.setSubjectLocalId(getJAXBValue(source.getSubjectLocalId()));
   }
 }
 @Override
 public void toSifModel(TimeTableSubject source, TimeTableCellType target) {
   if (source != null && target != null) {
     IObjectFactory objectFactory = getObjectFactory();
     target.setTimeTableSubjectRefId(source.getRefId());
     target.setSubjectLocalId(
         objectFactory.createTimeTableCellTypeSubjectLocalId(source.getSubjectLocalId()));
   }
 }