return new WebMvcConfigurerAdapter() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                String[] origins = new String[originList.size()];
                origins = originList.toArray(origins);
                registry.addMapping("/provideToken").allowedOrigins(origins);
            }
        };

@RequestMapping("/provideToken")
public void provideToken() {
  String user = request.getParameter("username");
  String password = request.getParameter("password");
  User user = userDao.findByNameAndPassword(user, password);
  if(user != null) {
   if(user.getServer().equals(request.getHeader("ORIGIN")) {
         //send token
   }
  }
}