Let's create a base controller (HomeController) for the secured JSP page (home.jsp). Please note that the return of the mapping method should be a string, and it should map to the actual name of the JSP file. In our case, it is home.jsp, a secured resource that the caller navigates when they log in:

@Controller
public class HomeController {

   @GetMapping("/")
   public String home(Model model, Principal principal) {
       if(principal != null)
           model.addAttribute("msg", "Welcome " + principal.getName());
       return "home";
   }
}