return nil
}

// watchRootCertAndgenKeyCert will watch for the root certs, and regenerate Istiod DNS TLS certificates if the root
// has changed. This is not used if TLS certificates are loaded from ./var/run/secrets/istiod/tls.
// TODO(hzxuzonghu): support async notification instead of polling the CA root cert.
func (s *Server) watchRootCertAndGenKeyCert(stop <-chan struct{}) {