LTCG tax on sale of foreign ESOP s by a resident individual

Raghuramsharma Bhogaiahgari (3 Points)

28 February 2020  
One of our client used to residing in America,working in a foreign company which is listed in that country's stock exchange. Meanwhile his employer allotted ESOPs to him around 2013. Now he is a Resident Indian for the past few years.There is no material annual income arising out of that stocks.Hence he is not consider that income while filing his Income tax returns.

In the present financial year he sold all of his shares allotted via ESOP. Net gain from the sale of those shares are approximately 23,00,000..
1. Whether foreign stock exchange is considered as "Recognised stock exchange or not?
2. What are the consequences of not showing the regular income from those stocks whether it covered under "Undisclosed Income provisions" or not?
3.whether the Grandfathering provisions are applicable to this case and how?
Please help me to proceed further by explaining the taxability of above case