curl --request POST \
  --url https://api.hubapi.com/crm/v3/objects/contacts/batch/create \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "inputs": [
    {
      "associations": [
        {
          "types": [
            {
              "associationCategory": "",
              "associationTypeId": 123
            }
          ],
          "to": {
            "id": "<string>"
          }
        }
      ],
      "objectWriteTraceId": "<string>",
      "properties": {}
    }
  ]
}'

{
  "completedAt": "2023-11-07T05:31:56Z",
  "requestedAt": "2023-11-07T05:31:56Z",
  "startedAt": "2023-11-07T05:31:56Z",
  "links": "",
  "results": [
    {
      "archived": false,
      "createdAt": "2019-10-30T03:30:17.883Z",
      "id": "512",
      "properties": {
        "property_checkbox": "false",
        "property_date": "1572480000000",
        "property_dropdown": "choice_b",
        "property_multiple_checkboxes": "chocolate;strawberry",
        "property_number": "17",
        "property_radio": "option_1",
        "property_string": "value"
      },
      "updatedAt": "2019-12-07T16:50:06.678Z"
    }
  ],
  "status": ""
}