wallabag/src/Wallabag/AnnotationBundle/DependencyInjection/Configuration.php

<?php

namespace Wallabag\AnnotationBundle\DependencyInjection;

use Symfony\Component\Config\Definition\Builder\TreeBuilder;
use Symfony\Component\Config\Definition\ConfigurationInterface;

class Configuration implements ConfigurationInterface
{
    /**
     * {@inheritdoc}
     */
    public function getConfigTreeBuilder()
    {
        return new TreeBuilder('wallabag_annotation');
    }
}