How to remove Spring CrudRepository unchecked conversion beside using suppress annotation

Question

This is my code :

public interface UserRepo extends CrudRepository<User, Long> {

    boolean exist(Long id);

    @Override
    User save(User user);

}

In eclipse, there is a warning on the return type User.

Description Resource Path Location Type Type safety: The return type User for save(User) from the type UserRepo needs unchecked conversion to conform to S from the type CrudRepository UserRepo.java

May I know

1. what is the reason ecplise warning on return type unchecked conversion?
2. what is the correct way to get rid of the warning?

TQ

Answer 1

As @dunny figured out in his comment, this statement makes no sense in the interface, as it is already implemented in org.springframework.data.repository.CrudRepository.save(S)

Eclipse gives this warning as it can not know, that the S in the super implementation is a User in this case.

In order to answer your 2. question, you can do a

@Override
<S extends User> S save(S user);

Then you get rid of the warning, but even then, it does not make more sense to provide this signature.

Just skip this statement, as it is already there.