@Transactional
 @Override
 public String findToken(UserAuth userAuth) throws UserNotFoundException {
   Authentication userAuthentication =
       authenticationRepository.findByIdUser(userService.findByUserAuth(userAuth));
   if (userAuthentication == null) throw new UserNotFoundException();
   return userAuthentication.getToken();
 }
 @Transactional
 @Override
 public Authentication create(UserAuth userAuth) throws UserNotFoundException {
   Authentication userAuthentication = new Authentication();
   userAuthentication.setIdUser(userService.findByUserAuth(userAuth));
   userAuthentication.setToken(new Integer(userAuth.getUsername().hashCode()).toString());
   authenticationRepository.save(userAuthentication);
   return userAuthentication;
 }