public function process(ContainerBuilder $container)
    {
        $metaTagHandlers = $container->findTaggedServiceIds('netgen_open_graph.meta_tag_handler');
        if (!empty($metaTagHandlers) && $container->hasDefinition('netgen_open_graph.handler_registry')) {
            $handlerRegistry = $container->getDefinition('netgen_open_graph.handler_registry');
            foreach ($metaTagHandlers as $serviceId => $metaTagHandler) {
                if (!isset($metaTagHandler[0]['alias'])) {
                    throw new LogicException(
                        'netgen_open_graph.meta_tag_handler service tag needs an "alias" attribute to identify the handler. None given.'
                    );
                }
                $handlerRegistry->addMethodCall(
                    'addHandler',
                    array(
                        $metaTagHandler[0]['alias'],
                        new Reference($serviceId),
                    )
                );
            }
        }
    }