promote AbstractController in 4.2 branch

Author: OskarStark

http_cache/validation.rst

@@ -62,7 +62,7 @@ To see a simple implementation, generate the ETag as the md5 of the content::
     // src/Controller/DefaultController.php
     namespace App\Controller;
 
-    use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+    use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
     use Symfony\Component\HttpFoundation\Request;
 
     class DefaultController extends AbstractController

routing/conditions.rst

@@ -15,10 +15,10 @@ define arbitrary matching logic, use the ``conditions`` routing option:
         // src/Controller/DefaultController.php
         namespace App\Controller;
 
-        use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+        use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
         use Symfony\Component\Routing\Annotation\Route;
 
-        class DefaultController extends Controller
+        class DefaultController extends AbstractController
         {
             /**
              * @Route(

web_link.rst

@@ -153,10 +153,10 @@ You can also add links to the HTTP response directly from controllers and servic
 
     use Fig\Link\GenericLinkProvider;
     use Fig\Link\Link;
-    use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+    use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
     use Symfony\Component\HttpFoundation\Request;
 
-    class BlogController extends Controller
+    class BlogController extends AbstractController
     {
         public function index(Request $request)
         {