@Valid Hibernate validation in a Spring REST controller

AdminExceptionHandler.java

@ControllerAdvice
public class AdminExceptionHandler {

    @ExceptionHandler(AdminNotFoundException.class)
    @ResponseBody
    public ResponseEntity<ErrorInfo> adminNotFoundException(HttpServletRequest request, AdminNotFoundException e) {
        String url = request.getRequestURL().toString();
        String errorMessage = localizeErrorMessage("error.admin.not.found", new Object[] { e.getAdminId() });
        return new ResponseEntity<ErrorInfo>(new ErrorInfo(url, errorMessage), HttpStatus.NOT_FOUND);
    }

    @ExceptionHandler(MethodArgumentNotValidException.class)
    @ResponseBody
    public ResponseEntity<ErrorFormInfo> methodArgumentNotValidException(HttpServletRequest request, MethodArgumentNotValidException e) {
        String url = request.getRequestURL().toString();
        String errorMessage = localizeErrorMessage("error.admin.invalid.form.argument");
        ErrorFormInfo errorFormInfo = new ErrorFormInfo(url, errorMessage);
        BindingResult result = e.getBindingResult();
        List<FieldError> fieldErrors = result.getFieldErrors();
        errorFormInfo.getFieldErrors().addAll(populateFieldErrors(fieldErrors));
        return new ResponseEntity<ErrorFormInfo>(errorFormInfo, HttpStatus.BAD_REQUEST);
    }

    public List<ErrorFormField> populateFieldErrors(List<FieldError> fieldErrorList) {
        List<ErrorFormField> errorFormFields = new ArrayList<ErrorFormField>();
        StringBuilder errorMessage = new StringBuilder("");
        for (FieldError fieldError : fieldErrorList) {
            errorMessage.append(fieldError.getCode()).append(".");
            errorMessage.append(fieldError.getObjectName()).append(".");
            errorMessage.append(fieldError.getField());
            errorFormFields.add(new ErrorFormField(fieldError.getField(), localizeErrorMessage(errorMessage.toString())));
            errorMessage.delete(0, errorMessage.capacity());
        }
        return errorFormFields;
    }

    private String localizeErrorMessage(String errorCode) {
        return localizeErrorMessage(errorCode, null);
    }

    private String localizeErrorMessage(String errorCode, Object args[]) {
        Locale locale = LocaleContextHolder.getLocale();
        String errorMessage = messageSource.getMessage(errorCode, args, locale);
        return errorMessage;
    }

}