password smb driver - session name split paremeter

[msuliga]

Currently my installation used Samba 4.2 for user directory.

The smb engine in password plugin sends username@domainname as the user name to change password and my Samba fails to accept it.
I introduced a mod to the plugin by adding the second line (below) in the drivers/smb.php:

$username = $_SESSION['username'];
// added little hack, this only keeps the login name as a paremeter
$username = explode( '@', $username)[0];
       
It would be nice if there was a parameter allowing the reduction of session user name to only user name for this password change.
The parameter 'session_domain' in global roundcube configuration does not do the trick