This endpoint is only available to merchants who do not pass in the
mchid.API Endpoint
URL:/trade/v1/add_noteMethod:
POSTContent-Type:
application/x-www-form-urlencoded
Add custom remarks to a completed transaction. Remarks will show in the Merchant Portal.
mchid./trade/v1/add_notePOSTapplication/x-www-form-urlencoded