src/ServiceProvider.php
public function boot()
    {
        $this->app->make(ChannelManager::class)->extend('fcm', function () {
            return new FCMChannel($this->app->make('fcm.sender'), $this->app->make('events'));
        });
    }
public function boot()
    {
        $this->app->make(ChannelManager::class)->extend('fcm', function () {
            return new FCMChannel($this->app->make('fcm.sender'), $this->app->make('events'));
        });
    }
Bootstrap the application services.