If you find yourself in the situation, where you need to extend the Laravel's 11 \Illuminate\Http\Request class, you can create the Request.php file in the /app/Http/ directory:
<?php
// /app/Http/Request.php
namespace App\Http;
class Request extends \Illuminate\Http\Request
{
// ...
}
And replace the line "use Illuminate\Http\Request;" with "use App\Http\Request;" at the beginning of the /public/index.php file.