public function normalizeId($id)
    {
        if (!\is_string($id)) {
            $id = (string) $id;
        }
        if (isset($this->normalizedIds[$normalizedId = strtolower($id)])) {
            $normalizedId = $this->normalizedIds[$normalizedId];
            if ($id !== $normalizedId) {
                @trigger_error(sprintf('Service identifiers will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since Symfony 3.3.', $id, $normalizedId), E_USER_DEPRECATED);
            }
        } else {
            $normalizedId = $this->normalizedIds[$normalizedId] = $id;
        }

        return $normalizedId;
    }