我试图创建可选的登录您可以登录（用户名或电话号码或电子邮件）在JavaSpring，我这样做了，但它没有工作，我搜索了很多关于它，但没有答案，我很肯定有办法做到这一点。
代码如下：

@Service
public class MyUserDetailsService implements UserDetailsService {

   @Autowired
   private UserRepository userRepository;

   @Override
   if(loadUserByUsername(String username)){
          public UserDetails loadUserByUsername(String username) {
             User user = userRepository.findByUsername(username);
             if (user == null) {
                throw new UsernameNotFoundException(username);
             }
             return new MyUserPrincipal(user);
           }
   } elseif(loadUserByUsername(String phone)){
          public UserDetails loadUserByUsername(String phone) {
                User user = userRepository.findByUsername(phone);
                if (user == null) {
                throw new PhoneNotFoundException(phone);
          }
          return new MyUserPrincipal(user);
   } elseif(loadUserByUsername(String email)){
            public UserDetails loadUserByUsername(String email) {
                User user = userRepository.findByUsername(email);
                if (user == null) {
                     throw new EmailNotFoundException(email);
                }
                return new MyUserPrincipal(user);
            }
   } else {
       return ex.CredentialNotFoundExptions;
   }

我这样做是为了让用户有三种登录方式的选择，但它一直给我错误，还没有找到答案。}