HandlerMethodArgumentResolver implementation returns an empty user object - spring-mvc

Question

I have created an implementation of HandlerMethodArgumentResolver to return the current logged in user for controller methods annotated with #CurrentUser. However, when the resolveArgument method of the HandlerMethodArgumentResolver gets called, an empty user is returned. I have verified that my custom UserDetailsService implementation does retrieve a full user object.
The code I'm using is as follows.
The #CurrUser annotation:
#Target({ElementType.PARAMETER, ElementType.TYPE})
#Retention(RetentionPolicy.RUNTIME)
#Documented
#AuthenticationPrincipal
public #interface CurrentUser {
}
The HandlerMethodArgumentResolver implementation with empty user:
public class CurrentUserMethodArgumentResolver implements HandlerMethodArgumentResolver {
#Inject
private UserService userService;
#Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.getParameterAnnotation(CurrentUser.class) != null
&& parameter.getParameterType().equals(User.class);
}
#Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
if (this.supportsParameter(parameter)) {
Principal principal = webRequest.getUserPrincipal();
User user = (User) ((Authentication) principal).getPrincipal(); // This user is empty!!!
return user;
} else {
return WebArgumentResolver.UNRESOLVED;
}
}
}
The calling Controller method:
#RequestMapping(value = "/user", method = RequestMethod.GET)
public HttpEntity<Resource<User>> currentUser(#CurrentUser User self) {
log.debug("CurrentUserController > currentUser GET> " + self);
}
The loadUserByUsername of UserDetailsService that retrieves the populated user (I verified this is called first):
#Override
public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
User user = userService.findByUsername(username);
CustomUserDetails ud = new CustomUserDetails(user);
return ud;
}
The WebMvcConfigurerAdapter configuration:
#Override
public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
argumentResolvers.add(currentUserMethodArgumentResolver());
}
#Bean
public CurrentUserMethodArgumentResolver currentUserMethodArgumentResolver() {
return new CurrentUserMethodArgumentResolver();
}

Answer 1

I discovered what the issue was - the problem was in how I implemented `CustomUserDetails':
public static class CustomUserDetails extends User implements UserDetails {
...
}
I was extending my custom User class and implementing UserDetails. I'm not sure why, but Spring didn't like this. I since fixed the code by creating and populating a new org.springframework.security.core.userdetails.User, and returning this from the call to `loadUserByUsername'.