public function create($order_id, array $lineItem, array $options = array())
  {
    $attributes = array_intersect_key($lineItem, array_flip(self::$keysToPersist));

    list($code, $createdLineItem) = $this->httpClient->post("/orders/{$order_id}/line_items", $attributes, $options);
    return $createdLineItem;
  }