Saving created_by field via api

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1

hi there,
cockpit is not saving created_by field via api save request.
my request is

{"data": {"content":"A new item","_by":"5fb17db2316366342100001f"}}

and the response is

 {
    "content": "A new item",
    "_by": null,
    "_modified": 1617304321,
    "published": false,
    "customer_id": "",
    "_created": 1617304321,
    "_id": "60661b016337376d19000381"
}

how can i record user id via api request ?