{
  "updates": [
    {
      "operation": "OPERATION_CREATE",
      "relationship": {
        "resource": {
          "objectType": "document",
          "objectId": "doc123"
        },
        "relation": "viewer",
        "subject": {
          "object": {
            "objectType": "user",
            "objectId": "user456"
          }
        }
      }
    }
  ]
}