SecurityContextHolderAwareRequestWrapper

org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestWrapper#getUserPrincipal

old:

public Principal getUserPrincipal() {
        Authentication auth = getAuthentication();

        if ((auth == null) || (auth.getPrincipal() == null)) {
            return null;
        }

        return auth;
    }

new: 

   public Principal getUserPrincipal() {
      Authentication auth = getAuthentication();

      if ((auth == null) || (auth.getPrincipal() == null)) {
         return null;
      }

      Object principal = auth.getPrincipal();
      return principal instanceof Principal ? (Principal)principal : auth;
   }