moved Swiftmailer finish call to a proper listener

src/Silex/Provider/SwiftmailerServiceProvider.php

@@ -13,13 +13,17 @@ namespace Silex\Provider;
 
 use Silex\Application;
 use Silex\ServiceProviderInterface;
+use Silex\EventListenerProviderInterface;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\HttpKernel\Event\PostResponseEvent;
 
 /**
  * Swiftmailer Provider.
  *
  * @author Fabien Potencier <fabien@symfony.com>
  */
-class SwiftmailerServiceProvider implements ServiceProviderInterface
+class SwiftmailerServiceProvider implements ServiceProviderInterface, EventListenerProviderInterface
 {
     public function register(Application $app)
     {
@@ -84,9 +88,9 @@ class SwiftmailerServiceProvider implements ServiceProviderInterface
         });
     }
 
-    public function boot(Application $app)
+    public function subscribe(Application $app, EventDispatcherInterface $dispatcher)
     {
-        $app->finish(function () use ($app) {
+        $dispatcher->addListener(KernelEvents::TERMINATE, function (PostResponseEvent $event) use ($app) {
             // To speed things up (by avoiding Swift Mailer initialization), flush
             // messages only if our mailer has been created (potentially used)
             if ($app['mailer.initialized']) {
@@ -94,4 +98,8 @@ class SwiftmailerServiceProvider implements ServiceProviderInterface
             }
         });
     }
+
+    public function boot(Application $app)
+    {
+    }
 }