code: public String path(M method, T target, Object... params) {
      MethodlessRouter<T> router = (method == null)? anyMethodRouter : routers.get(method);
      if (router == null) router = anyMethodRouter;
  
      String ret = router.path(target, params);
      if (ret != null) return ret;
  
      return (router == anyMethodRouter)? null : anyMethodRouter.path(target, params);
    }
docs: Reverse routing.