Service, DAO, Entity, BO . Again

@Entity
@Table(name = "Department", schema = "dbo", catalog = "mydb")
@NamedQueries({
        здесь пачка @NamedQuery
                
})
public class Department implements java.io.Serializable {
    private static final long serialVersionUID = 1L;
    
     //ссылаются на названия named query
    public static final String findAll = "Department.findAll";
    public static final String findByID = "Department.findById";
    public static final String findByIDWithDetail = "Department.findByIdWithDetail";
    public static final String findAllWithDetail = "Department.findAllWithDetail";
    public static final String findByCriteria = "Department.findByCriteria";
    public static final String findByCriteriaWithDetail = "Department.findByCriteriaWithDetail";
 
    private Short dptId;
    private Department department;
    private String dptName;
    private String dptAdr;
    private Set<Department> departments = new HashSet<Department>(0);
    private Set<Employee> employees = new HashSet<Employee>(0);
 
    public Department() {
    }
 
    public Department(Short dptId, String dptName, String dptAdr) {
        this.dptId = dptId;
        this.dptName = dptName;
        this.dptAdr = dptAdr;
    }
    
    //остальные set / get

public interface IDepartmentDAO {
    Department insert(Department info);
    Department update(Department info) throws SaveException;
    void delete (Department info) throws DeleteException;
 
    List<Department> find();
    List<Department> findWithDetail();
 
    Department find(Short id);
 
    List<Department> find(String criteria);
    List<Department> findWithDetail(String criteria);
 
}
}

@Repository
@Transactional
public class DepartmentDAO implements IDepartmentDAO {
    @PersistenceContext
    private EntityManager em;
 
    @Override
    public Department insert(Department info) {
        em.persist(info);
        return info;
    }
 
    @Override
    public Department update(Department info){
        em.merge(info);
        return info;
    }
 
    @Override
    public void delete(Department info) {
        em.remove(info);
    }
 
    @Override
    @Transactional(readOnly=true)
    public List<Department> find() {
        List<Department> contacts = null;
        try{
            contacts = em.createNamedQuery(Department.findAll, Department.class).getResultList();
        } catch (NoResultException nr){
            contacts = new ArrayList<>(0);
        }
        return contacts;
    }
    //остальные реализации

/**
 *   Класс DepartmentBO для хранения информации о подразделении где работают сотрудники
 *   @version 1.00
 */
public class DepartmentBO {
    private static final long serialVersionUID = 100L;
 
    private Short dptId;
    private String dptName;
    private String dptAdr;
    private DepartmentBO mainDepartment;
 
    public DepartmentBO(Short dptId, String dptName, String dptAdr, DepartmentBO mainDepartment) {
        this.dptId = dptId;
        this.dptName = dptName;
        this.dptAdr = dptAdr;
        this.mainDepartment = mainDepartment;
    }
    
    //  set / get чего позволено пользователю

public interface IDepartmentService {
    DepartmentBO insertDepartment(DepartmentBO info) throws SaveException;
    DepartmentBO updateDepartment (DepartmentBO info) throws SaveException;
    void removeDepartment (DepartmentBO info) throws DeleteException;
 
    DepartmentBO findDepartmentByID(Short id);
    DepartmentBO getParentDepartment(DepartmentBO department);
 
    List<DepartmentBO> findAllDepartments();
    List<DepartmentBO> findAllDepartmentsWithDetail();
 
    List<DepartmentBO> findDepartmentByCriteria(String criteria);
    List<DepartmentBO> findDepartmentByCriteriaWithDetail(String criteria);
}

@Service("HTTPDepartmentService")
public class DepartmentService implements IDepartmentService {
    private Log log = LogFactory.getLog(DepartmentService.class);
 
    @Autowired
    IDepartmentDAO depDAO;//будет подсунута спрингом реализация на основе hibernate
 
    @Override
    public DepartmentBO insertDepartment(DepartmentBO info) throws SaveException{
        Department department = DepartmentConverter.convertFromBO(info);
 
        log.info("Insert new Department");
        try{
            depDAO.insert(department);
        } catch (CannotCreateTransactionException | IllegalStateException ex){
            log.error(ex);
            throw new SaveException("Can not respond your request now. Try later.");
        }
        log.info("Department saved with id: " + info.getDptId());
 
        info = DepartmentConverter.convertToBO(department);
        return info;
    }
 
    @Override
    public DepartmentBO updateDepartment(DepartmentBO info) throws SaveException {
        Department department = DepartmentConverter.convertFromBO(info);
 
        log.info("Update Department with id: " + info.getDptId());
        try{
            depDAO.update(department);
        } catch (CannotCreateTransactionException | IllegalStateException ex){
            log.error(ex);
            throw new SaveException("Can not respond your request now. Try later");
        }
 
        info = DepartmentConverter.convertToBO(department);
        return info;
    }
    // остальные реализации

public class DepartmentConverter {
    /**
     * Конвертирует entity в BO
     * @param dep Entity объект для конвертации
     * @return Сконвертированный из Entity в BO объект
     */
    public static DepartmentBO convertToBO(Department dep){
        DepartmentBO result = null;
        if(dep != null){
            DepartmentBO mainDepartment = convertToBOWithoutLinks(dep.getDepartment());
            result = new DepartmentBO(dep.getDptId(),dep.getDptName(),dep.getDptAdr(), mainDepartment);
        }
        return result;
    }
 
    /**
     * Конвертирует Entity в BO без подтягивания связей по иерархии (заменяет ссылки на null)
     * @param department Объект для конвертирования
     * @return  Сконвертированный в BO объект без ссылок на другие (не POJO) объекты
     */
    public static DepartmentBO convertToBOWithoutLinks(Department department){
        DepartmentBO result = null;
        if(department != null)
            result = new DepartmentBO(department.getDptId(), department.getDptName(), department.getDptAdr(),null);
        return result;
    }
 
    /**
     * Конвертирует BO объект в Entity
     * @param depBO BO объект для конвертации
     * @return Entity объект сконвертированный из BO
     */
    public static Department convertFromBO(DepartmentBO depBO){
        if(depBO == null)
            throw new NullPointerException();
        Department result = new Department(depBO.getDptId(),depBO.getDptName(),depBO.getDptAdr());
        return result;
    }

CannotCreateTransactionException | IllegalStateException ex