private function addCustomProviderNode()
    {
        $builder = new TreeBuilder('custom_provider');
        $node    = $this->getRootNode($builder, 'custom_provider');

        $node
            ->children()
                ->scalarNode('type')->isRequired()->cannotBeEmpty()->end()
                ->arrayNode('options')
                    ->useAttributeAsKey('name')
                    ->prototype('scalar')->end()
                ->end()
            ->end()
        ;

        return $node;
    }