The id of the user document (ActiveStorage attachment) on the payable.

UUID of the company on whose behalf the request is made. Required for every Pay endpoint.
See The company-id header for details on how to obtain
a value for this header and the error responses to expect when it is missing or invalid.

If the deprecated company_id query parameter is also sent, both values must match;
the API returns 422 Unprocessable Entity when they disagree.