Merge branch '3.4' into 4.4

* 3.4:
  Add missing `->end()` method call

Author: javiereguiluz

components/config/definition.rst

@@ -743,7 +743,7 @@ By changing a string value into an associative array with ``name`` as the key::
                     ->then(function ($v) { return ['name' => $v]; })
                 ->end()
                 ->children()
-                    ->scalarNode('name')->isRequired()
+                    ->scalarNode('name')->isRequired()->end()
                     // ...
                 ->end()
             ->end()