code: public function register()
      {
          $configPath = __DIR__ . '/../config/omnipay.php';
          $this->publishes([$configPath => config_path('omnipay.php')]);
          
          $this->app->singleton('omnipay',function ($app){
              $defaults = $app['config']->get('omnipay.defaults', array());
              return new GatewayManager($app, new GatewayFactory, $defaults);
          });
      }
docs: Register the service provider.
  
  @return void