private function getFiles()
    {
        $file = $this->event->get('document');

        $response = $this->http->get($this->buildApiUrl('getFile'), [
            'file_id' => $file['file_id'],
        ]);

        $responseData = json_decode($response->getContent());

        if ($response->getStatusCode() !== 200) {
            throw new TelegramAttachmentException('Error retrieving file url: '.$responseData->description);
        }

        $url = $this->buildFileApiUrl($responseData->result->file_path);

        return [new File($url, $file)];
    }