public function appendConfiguration(ArrayNodeDefinition $rootNode)
    {
        $rootNode
            ->children()
                ->arrayNode('vcs')
                    ->children()
                        ->scalarNode('url')->end()
                        ->arrayNode('export')
                            ->children()
                                ->scalarNode('revfile')->isRequired()->end()
                            ->end()
                        ->end()
                    ->end()
                ->end()
            ->end()
        ;
    }