minor #14027 Use redirectToRoute (l-vo)

This PR was merged into the 3.4 branch.

Discussion
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Use redirectToRoute

instead of $this->redirect($this->generateUrl('...'))

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Commits
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964fbda Use redirectToRoute

Author: xabbuh

controller/upload_file.rst

@@ -170,7 +170,7 @@ Finally, you need to update the code of the controller that handles the form::
 
                 // ... persist the $product variable or any other work
 
-                return $this->redirect($this->generateUrl('app_product_list'));
+                return $this->redirectToRoute('app_product_list');
             }
 
             return $this->render('product/new.html.twig', [