add view function for withdrawal address

aptos-move/framework/supra-framework/sources/vesting_without_staking.move

@@ -182,6 +182,12 @@ module supra_framework::vesting_without_staking {
         borrow_global<VestingContract>(vesting_contract_address).vesting_schedule.period_duration
     }
 
+    #[view]
+    // Return the `withdrawal_address` of the contract
+    public fun get_withdrawal_addr(vesting_contract_addr: address): address acquires VestingContract {
+        borrow_global<VestingContract>(vesting_contract_addr).withdrawal_address
+    }
+
     #[view]
     // Return the `admin` address of the contract
     public fun get_contract_admin(vesting_contract_addr: address): address acquires VestingContract {
@@ -2337,6 +2343,7 @@ module supra_framework::vesting_without_staking {
         let vested_amount = 0;
         // Because the time is behind the start time, vest will do nothing.
         vest(contract_address);
+        assert!(get_withdrawal_addr(contract_address)==withdrawal_address,98);
         assert!(get_contract_admin(contract_address)==admin_address,99);
         assert!(coin::balance<SupraCoin>(contract_address) == 1000, 0);
         assert!(coin::balance<SupraCoin>(shareholder_address) == vested_amount, 0);