Unchecked call to 'save(E)' as

Question

MemberJoin Creadted But Error

1. MemberController.java

    @Autowired
    private MemberSv memberSv;
   
    @RequestMapping(value = "/join", method = RequestMethod.POST)
    public String membersave(MemberDTO memberDTO)
    {
        memberSv.member_save(memberDTO);
        return "join_form";
    }
   

2. MemvberSv.java

    public interface MemberSv {
        MemberDTO member_save(MemberDTO memberDTO);
    }
   

3. MemberSvImp.java

    @Service
    public class MemberSvImp implements MemberSv {
   
   
        CommonRepository commonRepository;
   
        @Override
        public MemberDTO member_save(MemberDTO memberDTO) {
            commonRepository.save(memberDTO);
            return memberDTO;
        }
   
   
    }
   

4. CommonRepository.java

    @NoRepositoryBean
    public interface CommonRepository<T, ID extends Serializable> extends                                 
    MongoRepository<T, ID> {
        <E extends T> E save(E entity);
    }
   

5. Error java.lang.NullPointerException: null at

com.example.accountproject.models.services.MemberSvImp.member_save(MemberSvImp.java:19) ~[main/:na]