[TwigExtraBundle] Add the return type information in getConfigTreeBuilder()

extra/twig-extra-bundle/DependencyInjection/Configuration.php

@@ -17,6 +17,9 @@ use Twig\Extra\TwigExtraBundle\Extensions;
 
 class Configuration implements ConfigurationInterface
 {
+    /**
+     * @return TreeBuilder
+     */
     public function getConfigTreeBuilder()
     {
         $treeBuilder = new TreeBuilder('twig_extra');