HttpServletRequest userprincipal is null at first load

im using javax.servlet.http.HttpServletRequest; to get the request in java controller, i just want to create controller that returns actual user name, im using method getUserPrincipal() in order to get the user in the actual session, it doesn't work at the first page load (returns null) but when i reload the page it works perfectly.

Im using

• spring framework 5.3.9
• javaee-api 8.0
• weblogic 14.1.1
• vuejs 3.2.37

Here is my java controller

@GetMapping("/username")
    public ResponseEntity<?> getname(HttpServletRequest request) {
        Map<String, String> response = new HashMap<String, String>();

        String username = "";
        try {

            Principal p = request.getUserPrincipal();
            if (p == null || p.getName() == null || p.getName().equals("")) {

                username = "undefined";

            } else {
                username = p.getName();
            }
            response.put("username", username);

            return new ResponseEntity<Object>(
                    response, HttpStatus.OK);
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
            response.put("username", "");
            return new ResponseEntity<Object>(response, HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

I have tried something a little tricky, reload the page in my Vue file when username is undefined, it works but i need this to work at first load.

Can you help me with this issue?

Thanks