embed/serve.go
func createAccessController(lg *zap.Logger, s *etcdserver.EtcdServer, mux *http.ServeMux) http.Handler {
	return &accessController{lg: lg, s: s, mux: mux}
}
func createAccessController(lg *zap.Logger, s *etcdserver.EtcdServer, mux *http.ServeMux) http.Handler {
	return &accessController{lg: lg, s: s, mux: mux}
}
// createAccessController wraps HTTP multiplexer:
// - mutate gRPC gateway request paths
// - check hostname whitelist
// client HTTP requests goes here first