public function create($productId, ProductImage &$productImage)
    {
        $data = $productImage->exportData();
        $endpoint = '/admin/products/'.$productId.'/images.json';
        $response = $this->request(
            $endpoint, 'POST', array(
            'image' => $data
            )
        );
        $productImage->setData($response['image']);
    }