class 'Pusher\Pusher' not found required in laravel package

I'm creating my own Laravel package and I required Pusher server in my package, in my composer.json there is a pusher required and I also checked it in vendor folder also exist ... and when I'm trying to use it in my package controller like use Pusher\Pusher; it says that class 'Pusher\Pusher' not found!!!

Does anyone have a solution?? Thanks in advance.

via Chebli Mohamed