HarmonyOS 鸿蒙Next下载文件的回调进度中sizes打印的是-1，为什么? 不应该是文件的总大小吗?

HarmonyOS 鸿蒙Next下载文件的回调进度中sizes打印的是-1，为什么? 不应该是文件的总大小吗?

try {
  let config: request.agent.Config = {
    action: request.agent.Action.DOWNLOAD,
    url: url,
    mode: request.agent.Mode.BACKGROUND,
    gauge: true,
    overwrite: true,
    headers: {
      'Content-Type': 'multipart/form-data',
      'package_id': 'com.ce.ice',
      'device_identification': 'harmonry_os_ice_demo',
      'Authorization': axiosManager.getAuthorizationStr(),
      'User-Agent': safetyTunnelManager.getTunnelCommonUserAget() // 设置安全隧道User-Agent
    },
    saveas: this.getIMImageSandboxPath(url),
    proxy: safetyTunnelManager.getTunnelCommonProxy()  //设置安全隧道代理
  };
  request.agent.create(getContext(), config)
    .then((task: request.agent.Task) => { // 进度
      let progressCallBack = (progress: request.agent.Progress) => {
        console.info('progressCallBack - ' + JSON.stringify(progress))
      };
      task.on('progress',
        progressCallBack) // 暂停
      let pauseCallBack = (progress: request.agent.Progress) => {
        console.info('pauseCallBack', JSON.stringify(progress));
      };
      task.on('pause',
        pauseCallBack) // 完成
      let completedCallBack = (progress: request.agent.Progress) => {
        console.info('completedCallBack', JSON.stringify(progress));
        let resultPath = this.getIMImageSandboxPath(url)
        finish(resultPath)
      };
      task.on('completed',
        completedCallBack) // 失败
      let failedCallBack = (progress: request.agent.Progress) => {
        console.info('failedCallBack', JSON.stringify(progress));
      };
      task.on('failed', failedCallBack)
      task.start()
    }).catch((err: BusinessError) => {
    console.error(`Failed to create a download task, Code: ${err.code}, message: ${err.message}`);
  })
} catch (err) {
  console.error(`Failed to request the download. err: ${JSON.stringify(err)}`);
  //打印的进度的日志如下
  {
    "state":
    32, "index":
    0, "processed":
    2587088, "sizes":[-
    1],
    "extras":
    {
      "accept-ranges":
      "bytes", "cache-control":
      "max-age=8640000", "connection":
      "keep-alive", "content-disposition":
      "inline; filename=image0.jpg.jpg", "content-transfer-encoding":
      "binary", "content-type":
      "image/jpg", "date":
      "Wed, 11 Sep 2024 01:11:35 GMT", "etag":
      "cid:0/id:30866449/type:1/biz:0", "expires":
      "Fri, 20 Dec 2024 01:11:35 GMT", "last-modified":
      "Wed, 11 Sep 2024 01:11:35 GMT", "pragma":
      "", "server":
      "elb", "transfer-encoding":
      "chunked", "vary":
      "Accept-Encoding"
    }
  }
  progressCallBack - {
    "state": 32,
    "index": 0,
    "processed": 3688289,
    "sizes": [-1],
    "extras": {
      "accept-ranges": "bytes",
      "cache-control": "max-age=8640000",
      "connection": "keep-alive",
      "content-disposition": "inline; filename=image0.jpg.jpg",
      "content-transfer-encoding": "binary",
      "content-type": "image/jpg",
      "date": "Wed, 11 Sep 2024 01:11:35 GMT",
      "etag": "cid:0/id:30866449/type:1/biz:0",
      "expires": "Fri, 20 Dec 2024 01:11:35 GMT",
      "last-modified": "Wed, 11 Sep 2024 01:11:35 GMT",
      "pragma": "",
      "server": "elb",
      "transfer-encoding": "chunked",
      "vary": "Accept-Encoding"
    }
  }