Org.springframework.web.HttpMediaTypeNotSupportedException

 when i am trying to get values by id ..i got error like this in postman  

{ "отметка времени": 1547708533031,
«статус»: 500,
"error": "Внутренняя ошибка сервера", «исключение»: «org.springframework.http.converter.HttpMessageNotWritableException»,
"message": "Не удалось записать JSON: не найден сериализатор для класса org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer и не обнаружены свойства для создания BeanSerializer (чтобы избежать исключения, отключите SerializationFeature.FAIL_ON_EMPTY_BEANS); вложенное исключение com.fasterxml .jackson.databind.JsonMappingException: не найден сериализатор для класса org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer и не обнаружены свойства для создания BeanSerializer (чтобы избежать исключения, отключите SerializationFeature.FAIL_ON_EMPTY_BEANS) (через цепочку ссылок: com.Entites .ArtistRegister [\ "subcetgory \"] -> com.Cetegory.Entites.SubCetegory _ $$ _ jvst706_1 [\ "обработчик \"]) ",
"путь": "/ getartist / 2"
}

this is contoller for get data by id
@RestController
public class RegisterController {

    @Autowired
    ArtistService artser;

    @PostMapping(value = "/addArtist",produces = "application/json")
    @ResponseBody public ArtistRegister addArtist(@RequestBody ArtistRegister artist) {

        ArtistRegister artRegister = null;
        try {

            artRegister = artser.addArtist(artist);

        } catch (Exception e) {
            e.printStackTrace();
        }
        return artRegister;

    }  

    @RequestMapping(value = "/getartist/{artist_id}",method=RequestMethod.GET,produces = "application/json")
    @ResponseBody   public ArtistRegister getArtistDetails(@PathVariable ("artist_id") int artist_id ,HttpServletRequest request,
        HttpServletResponse response) throws Exception{
    return artser.getArtistDetails(artist_id);

    }   

    @RequestMapping(value = "/delete/{artist_id}",method=RequestMethod.DELETE,produces = "application/json")
        public void deleteById(@PathVariable (value = "artist_id") int artist_id,HttpServletRequest request,
                HttpServletResponse response) throws Exception{
            artser.deleteById(artist_id);
        }

    @RequestMapping(value = "/updateartist", method = RequestMethod.PUT, produces = "application/json")
    public ArtistRegister updateArtist(@RequestBody ArtistRegister artreg, HttpServletRequest request, HttpServletResponse response)
            throws Exception 
    {   
        return artser.updateArtist(artreg);
    }


this is service
@Service
@Transactional
public class ArtistService {

    @Autowired
    private ArtistRepository artrep;

    @Autowired
    private RegisterDAO artdao;

    public ArtistRegister addArtist(ArtistRegister artreg) {

        ArtistRegister artReg = null;
        try {
            artReg = artrep.save(artreg);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return artReg;
    }

    public ArtistRegister getArtistDetails(int artist_id) {
        return artdao.getArtistDetails(artist_id);

    }

    public void deleteById(int artist_id) {
        artdao.deleteById(artist_id);
    }

    public ArtistRegister updateArtist(ArtistRegister artreg) {
        return artdao.updateArtist(artreg);

    }

}


this is DAO
@Repository
@Transactional
public class RegisterDAO {

    private static final Logger logger = LoggerFactory.getLogger(SubCetegoryDAO.class);

    @Autowired
    SessionFactory sessionFactory;

    @Autowired
    EntityManager entitymanager;

    public ArtistRegister getArtistDetails(int artist_id) {

        try 
        {
            String hql = "FROM ArtistRegister a where a.artist_id=?";
            return (ArtistRegister) entitymanager.createQuery(hql).setParameter(1, artist_id).getSingleResult();
        } 
        catch (EmptyResultDataAccessException e) 
        {
            return null;
        } 
        catch (Exception e) 
        {
            logger.error("Exception in getUser"+ e.getMessage());
            return null;
        }

    }