curl --request POST \
  --url https://api.comstruct.com/v1/invoices/callback \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '
{
  "external_id": "<string>",
  "success": true,
  "messages": [
    "<string>"
  ]
}
'

{
  "success": true,
  "message": "<string>"
}