curl --request POST \
  --url https://api.prod.getdex.com/v1/custom-fields/batch-update-contacts \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "custom_fields": [
    {
      "contact_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "custom_field_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "text_value": "<string>",
      "date_value": "<string>",
      "array_value": [
        "<string>"
      ]
    }
  ]
}
'

{
  "error": true,
  "data": {
    "count": 123
  }
}