According to which treaty were Tipu's children held in Calcutta as security pending payment of compensation to the Company?

Following the Third Anglo-Mysore War, the Treaty of Seringapatam was signed in 1792. Under this treaty, Tipu Sultan had to surrender half of his kingdom and pay a massive war indemnity. Two of his sons were taken as hostages by Lord Cornwallis as security until the payment was completed.