"error": {
"status": "INVALID_ARGUMENT", 
"message": "Request contains an invalid argument.", 
"code": 400, 
"details": [
  {
    "fieldViolations": [
      {
        "field": "update_mask", 
        "description": "pubsub_topic/notification_types are the only supported update_mask."
      }
    ], 
    "@type": "type.googleapis/google.rpc.BadRequest"
  }
]

}

/{accountId}/notificationSetting?update_mask="pubsub_topic,notification_types"