curl --request GET \
  --url https://api.closebot.com/agency/source/{id}/fields \
  --header 'X-CB-KEY: <api-key>'

{
  "contact": [
    {
      "name": "<string>",
      "fieldKey": "<string>",
      "dataType": "<string>"
    }
  ],
  "location": [
    {
      "name": "<string>",
      "fieldKey": "<string>",
      "dataType": "<string>"
    }
  ],
  "customValue": [
    {
      "name": "<string>",
      "fieldKey": "<string>",
      "dataType": "<string>"
    }
  ]
}