docs: public void throwExceptionIfAlreadyAuthenticate(HttpServletRequest req, HttpServletResponse resp, WebAppSecurityConfig config, String username) throws ServletException {
          Subject callerSubject = subjectManager.getCallerSubject();
          if (subjectHelper.isUnauthenticated(callerSubject))
              return;
          if (!config.getWebAlwaysLogin()) {
              AuthenticationResult authResult = new AuthenticationResult(AuthResult.FAILURE, username);
              authResult.setAuditCredType(req.getAuthType());
              authResult.setAuditCredValue(username);
              authResult.setAuditOutcome(AuditEvent.OUTCOME_FAILURE);
              Audit.audit(Audit.EventID.SECURITY_API_AUTHN_01, req, authResult, Integer.valueOf(HttpServletResponse.SC_UNAUTHORIZED));
              throw new ServletException("Authentication had been already established");
          }
          logout(req, resp, config);
      }