curl --request POST \
  --url https://openapi.pluuug.com/v1/contract/{contract_id}/history \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --header 'X-Signature: <api-key>' \
  --data '
{
  "content": "<string>",
  "created": "2023-11-07T05:31:56Z",
  "member": {
    "id": 123
  }
}
'

{
  "id": 123,
  "content": "<string>",
  "created": "2023-11-07T05:31:56Z",
  "member": {
    "id": 123,
    "nickname": "<string>",
    "email": "<string>",
    "isActive": true,
    "grade": {
      "id": 123,
      "title": "<string>"
    }
  }
}