Laravel Passport Install Class Not Found

I'm trying to configure my Laravel app to use Passport and have gotten stuck at loading the class in my AppServiceProvider.php. Here is what I've done...

<?php // AuthServiceProvider.php

namespace S1\Providers;

use Laravel\Passport\PassportServiceProvider;
use Illuminate\Support\Facades\Gate;
use Illuminate\Foundation\Support\Providers\AuthServiceProvider as 
ServiceProvider;

class AuthServiceProvider extends ServiceProvider
{
...
    public function boot()
    {
        $this->registerPolicies();
        Passport::routes();
        Passport::tokensCan([
            'client' => 'this is a api client test'
        ]);
    }
}

.

<?php .  // auth.php
 ...
return [

    'guards' => [
        'web' => [
             'driver' => 'passport',
            'provider' => 'users',
        ],
], ...

.

<?php // app.php

'providers' => [
...
Laravel\Passport\PassportServiceProvider::class,
....

.

<?php  // AppServiceProvider.php

namespace S1\Providers;

use Illuminate\Support\ServiceProvider;
use S1\Providers\AppServiceProvider;
use Laravel\Passport\PassportServiceProvider;

class AppServiceProvider extends ServiceProvider
{

    public function register()
    {
        // Enable Laravel Migrations Generator for development only
        if ($this->app->environment() !== 'production') {
            $this->app->register(\Way\Generators\GeneratorsServiceProvider::class);
            $this->app->register(\Xethron\MigrationsGenerator\MigrationsGeneratorServiceProvider::class);
        }
    }
}

The result of this is getting the following error:

  [Symfony\Component\Debug\Exception\FatalThrowableError]  
  Class 'S1\Providers\Passport' not found   

I did have this working but had to rebuid and now I can't get past this error. Something is going on with my namespaces but I can't figure out what.

via Chebli Mohamed