OneToOne Annotation is not working

Hibernate Tools
1

So i am tidying up my small Spring project and i noticed for some reason the OneToOne annotation is not doing its job for me which in turn causes issues in another model.

github link : https://github.com/eamonmckelvey/sports-app

Basically i have a User model class, a team model class and a player model class.
I want only one user to be able to create one team, and one team to have many players.
However i am able to add as many teams to my user as i want which is wrong.

All the answers provided require me to add a no arg constructor and a constructor for my users class but when i do this i get an error in my registration from class.

Please help.

  1. User Model
    ==================
    Entity
    Data
    NoArgsConstructor(access= AccessLevel.PRIVATE, force=true)
    RequiredArgsConstructor
    public class User implements UserDetails {

        OneToOne(cascade = CascadeType.ALL,mappedBy = "user")
   private Team team;

 private static final long serialVersionUID = 1L;
 Id
 GeneratedValue(strategy= GenerationType.AUTO)
 private Long id;
 private final String username;
 private final String password;
 //private final String fullname;




 Override
 public Collection<? extends GrantedAuthority> getAuthorities() {
     return Arrays.asList(new SimpleGrantedAuthority("ROLE_USER"));
 }
 Override
 public boolean isAccountNonExpired() {
     return true;
 }
 Override
 public boolean isAccountNonLocked() {
     return true;
 }
 Override
 public boolean isCredentialsNonExpired() {
     return true;
 }
 Override
 public boolean isEnabled() {
     return true;
    }
}

  2. Team Model
    ==================
    Data
    Entity
    Table(name=“User_Team”)

    public class Team implements Serializable {

    OneToOne(fetch= FetchType.LAZY)

    private User user;

    private static final long serialVersionUID = 1L;

    id

    GeneratedValue(strategy= GenerationType.AUTO)
    private Long id;
    private String teamName;
    private String location;
    private String nickName;
    private String yearEstablished;
    public Sport sport;
    private Divison divison;

  3. Team Controller
    ======================

    Slf4j
    Controller
    SessionAttributes(“Team”)

    public class TeamController {

    private TeamRepository teamRepository;

    public TeamController(TeamRepository teamRepository) {
    this.teamRepository = teamRepository;
    }

    Autowired
    TeamRepository service;

    GetMapping("/team")
    public String displayTeam(Model model) {

     model.addAttribute("team", service.findAll());

 return "/team";
}

 GetMapping("/addTeam")
 public String showSignUpForm(User user) {
 return "addTeam";
}

 PostMapping("/addTeam")
 public String processOrder(Valid Team team, BindingResult result, SessionStatus 
 sessionStatus,
                        AuthenticationPrincipal User user, Model model) {
 if (result.hasErrors()) {
     return "addTeam";
 }

 team.setUser(user);
 service.save(team);
 model.addAttribute("team", service.findAll());
 return "team";

    }

  4. Registeration Form
    ==============================
    Data
    public class RegistrationForm {
    private String username;
    private String password;
    //private String fullname;

     public User toUser(PasswordEncoder passwordEncoder) {
 return new User(
         username, passwordEncoder.encode(password));

    }
    }

  5. Registration Controller
    ============================
    Controller
    RequestMapping("/register")
    public class RegistrationController {

     private UserRepository userRepo;
 private PasswordEncoder passwordEncoder;

 public RegistrationController( UserRepository userRepo, 
   PasswordEncoder passwordEncoder){
 this.userRepo = userRepo;
 this.passwordEncoder = passwordEncoder;

    }

     GetMapping
public String registerForm(){
  return "registration";

    }
    PostMapping
    public String processRegistration(RegistrationForm form){
    userRepo.save(form.toUser(passwordEncoder));
    return “redirect:/login”;
    }

  6. user details class
    ======================
    Service
    public class UserRepositoryUserDetailsService implements
    UserDetailsService {

    private UserRepository userRepo;
    Autowired
    public UserRepositoryUserDetailsService(UserRepository userRepo) {
    this.userRepo = userRepo;
    }
    Override
    public UserDetails loadUserByUsername(String username) throws
    UsernameNotFoundException {
    User user = userRepo.findByUsername(username);

     if (user != null) {
     return user;
 }
 throw new UsernameNotFoundException(
         "User '" + username + "' not found");

    }