Laravel Override Vendor Class RedirectResponse

i'm trying to override a function in RedirectResponse which extends the Response class in Symfony\Component\HttpFoundation.

To be more specific i want to override the setTargetUrl($url) function.

I've read that i have to do some configuration changes and possibly add my own ServiceProvider. But i cant figure out where i have to put my new RedirectResponse.

In Laravel 4 there was a File named bootstrap/start.php where i could change the Vendor Class with my own. But this functionality is no longer present in Laravel 5. So where should i start? May be i can get some hint to start going.

I am using Laravel 5.5.

via Chebli Mohamed