How to use FlutterVpn.connectIPSec() ?

[fajrur]

How to use this function in Android? I want to connect to my vpn that have secret key. I added my secret key to the form and used this function:

FlutterVpn.connectIPSec(
   server: _addressController.text,
   username: _usernameController.text,
   password: _passwordController.text,
   secret: _secretController.text);