"results": [
    {
      "error": {
        "code": "messaging/registration-token-not-registered",
        "message": "The provided registration token is not registered. A previously valid registration token can be unregistered for a variety of reasons. See the error documentation for more details. Remove this registration token and stop using it to send messages."
      }
    },
    {
      "error": {
        "code": "messaging/registration-token-not-registered",
        "message": "The provided registration token is not registered. A previously valid registration token can be unregistered for a variety of reasons. See the error documentation for more details. Remove this registration token and stop using it to send messages."
      }
    },
    {
      "messageId": "1708335104009267"
    }
  ],
  "canonicalRegistrationTokenCount": 0,
  "failureCount": 2,
  "successCount": 1,
  "multicastId": 6588644802774198000
}