WC_Product::get_file_download_path PHP Method

    public function get_file_download_path($download_id)
    {
        $files = $this->get_downloads();
        $file_path = isset($files[$download_id]) ? $files[$download_id]->get_file() : '';
        // allow overriding based on the particular file being requested
        return apply_filters('woocommerce_product_file_download_path', $file_path, $this, $download_id);
    }