Serializer serializer = new Persister(strategy);
registry.bind(AppointmentCategory.class, AppointmentCategoryConverter.class);
registry.bind(User.class, UserConverter.class);
registry.bind(AppointmentReminderTyps.class, AppointmentReminderTypeConverter.class);
registry.bind(Room.class, RoomConverter.class);
if (list != null && list.size() > 0) {
registry.bind(list.get(0).getStart().getClass(), DateConverter.class);
}
writeList(serializer, backup_dir, "appointements.xml", "appointments", list);