private function addNormalizedIds()
    {
        $code = '';
        $normalizedIds = $this->container->getNormalizedIds();
        ksort($normalizedIds);
        foreach ($normalizedIds as $id => $normalizedId) {
            if ($this->container->has($normalizedId)) {
                $code .= '            '.$this->doExport($id).' => '.$this->doExport($normalizedId).",\n";
            }
        }

        return $code ? "        \$this->normalizedIds = array(\n".$code."        );\n" : '';
    }