code: public E getUser(HttpServletRequest servletRequest) {
          AttributePrincipal principal = getUserPrincipal(servletRequest);
          E result = this.userDao.getByPrincipal(principal);
          if (result == null) {
              throw new HttpStatusException(Status.FORBIDDEN, "User " + principal.getName() + " is not authorized to use this resource");
          }
          return result;
      }
docs: Returns the user object, or if there isn't one, throws an exception.
  
  @param servletRequest the HTTP servlet request.
  @return the user object.
  
  @throws HttpStatusException if the logged-in user isn't in the user
  table, which means the user is not authorized to use eureka-protempa-etl.