KnpU\OAuth2ClientBundle\DependencyInjection\Configuration::getConfigTreeBuilder PHP Method

    public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('knpu_oauth2_client');
        $rootNode->children()->arrayNode('clients')->prototype('array')->prototype('variable')->end()->end()->end()->end();
        return $treeBuilder;
    }