Redirecting to another sub-domain with added flash attributes (Redirectattributes) does not work

Question

My question is related to adding attributes in the interface RedirectAttributes. I’m adding two attributes flash redirecting, but redirecting does not just change the URI, but the sub-domain as can be seen in the method below:

@RequestMapping(value = "/access-agency", method = RequestMethod.GET)
public String acessLoginPage(@RequestParam(required = true) String email, final RedirectAttributes redirectAttributes, HttpServletRequest request){
    Login login = loginFacade.findByEmail(email);
    Agency agency = agencyFacade.findAgencyByTenantId(login.getTenantId());

    redirectAttributes.addFlashAttribute("inputFieldReadOnly", Boolean.TRUE);
    redirectAttributes.addFlashAttribute("employeeEmail", email);
    return "redirect:http://" + agency.getSubdomain() + "."+ request.getServerName().replaceAll(".*\\.(?=.*\\.)", "") + ":" + request.getServerPort() + request.getContextPath()+"/login";  
}

Unfortunately it doesn’t work! Can anyone tell me if it’s because I’m redirecting to another sub-domain and the

Redirectattributes

only works with changing URI?