code: public String getJwtTokenUsingBuilder(String testName, LibertyServer server, String builderId, List<NameValuePair> extraClaims) throws Exception {
  
          String jwtBuilderUrl = SecurityFatHttpUtils.getServerUrlBase(server) + "/jwtbuilder/build";
  
          List<NameValuePair> requestParams = setRequestParms(builderId, extraClaims);
  
          WebClient webClient = new WebClient();
          Page response = invokeUrlWithParameters(testName, webClient, jwtBuilderUrl, requestParams);
          Log.info(thisClass, testName, "JWT builder app response: " + WebResponseUtils.getResponseText(response));
  
          Cookie jwtCookie = webClient.getCookieManager().getCookie("JWT");
          Log.info(thisClass, testName, "Built JWT cookie: " + jwtCookie);
          Log.info(thisClass, testName, "Cookie value: " + jwtCookie.getValue());
          return jwtCookie.getValue();
  
      }
docs: anyone calling this method needs to add upn to the extraClaims that it passes in (if they need it)