Demand on foreign income

Saswata Chatterjee (Student) (47 Points)

24 July 2021  
A company is involved in export for software maintainance service internationally and earns revenue in foreign currency. Now this service is exempted in the rule of gst. Now a demand from the council has been raised on the exhange gain on revenue. Is it vaible? or is there any defending argument that can be raised against this demand because as per my knowledge as a practitioner exchange gain on services rendered outside india doesn't attract gst.
Need some guidance urgently.