curl --request POST \
  --url https://v1.api.flux-os.com/contracts/{id}/parties \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --header 'x-user-id: <api-key>' \
  --data '
{
  "organization": "<unknown>",
  "role": "<unknown>",
  "entity": "<unknown>"
}
'

{
  "data": {
    "contract": "<unknown>",
    "id": "<string>",
    "organization": {
      "name": "<string>",
      "id": "<string>",
      "image_url": null
    },
    "entity": {
      "legal_name": "<string>",
      "id": "<string>"
    },
    "role": {
      "name": "<string>",
      "short_code": "<string>",
      "id": "<string>"
    },
    "created_at": "2023-11-07T05:31:56Z",
    "updated_at": "2023-11-07T05:31:56Z",
    "users": [
      {
        "party": "<unknown>",
        "id": "<string>",
        "user": {
          "first_name": "<string>",
          "last_name": "<string>",
          "id": "<string>",
          "roles": "<unknown>"
        },
        "created_at": "2023-11-07T05:31:56Z",
        "updated_at": "2023-11-07T05:31:56Z"
      }
    ]
  }
}