private function getSourceNode()
    {
        $node = $this->createTreeBuilderNode('_source');

        $node
            ->children()
                ->arrayNode('excludes')
                    ->useAttributeAsKey('name')
                    ->prototype('scalar')->end()
                ->end()
                ->arrayNode('includes')
                    ->useAttributeAsKey('name')
                    ->prototype('scalar')->end()
                ->end()
                ->scalarNode('compress')->end()
                ->scalarNode('compress_threshold')->end()
                ->scalarNode('enabled')->defaultTrue()->end()
            ->end()
        ;

        return $node;
    }