Laravel 5.2 with cashier 6.0 , swap withCoupon issue

the new subscription working fine with "withCoupon" and "skipTrial"

$resultat = $user->newSubscription('main', $plandid)
                             ->skipTrial()
                             ->withCoupon($coupon)
                             ->create($token);

but not working with swap

$resultat = $user->subscription('main')
                        ->skipTrial()
                        ->withCoupon($coupon)
                        ->swap($plandid);

via Chebli Mohamed