Почему spring data может генерировать sql запрос без manytomany?

@Service
public class UserDetailsServiceImpl implements UserDetailsService {
 
    @Autowired
    private UserRepo userRepo;
 
    @Override
    @Transactional(readOnly = true)
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        User user = userRepo.findByUsername(username);
        if (user == null) {
            throw new UsernameNotFoundException("User not authorized.");
        }
        Set<GrantedAuthority> roles = new HashSet<>();
        user.getRoles().forEach(r -> roles.add(new SimpleGrantedAuthority(r.getName())));
 
        return new org.springframework.security.core.userdetails.User(user.getUsername(), user.getPassword(), roles);
    }
}

    @ManyToMany(targetEntity = Role.class,
            cascade = {CascadeType.PERSIST, CascadeType.DETACH, CascadeType.MERGE, CascadeType.REFRESH})
    @JoinTable(
            name = "user_roles",
            joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(name = "role_id", referencedColumnName = "id")
    )
    private List<Role> roles;

    @ManyToMany(targetEntity = User.class, mappedBy = "roles",
            cascade = {CascadeType.PERSIST, CascadeType.DETACH, CascadeType.MERGE, CascadeType.REFRESH}
    )
    private List<User> users;