code: public boolean setMaxNetworkThreadCount(final int count) {
          if (!FileDownloadList.getImpl().isEmpty()) {
              FileDownloadLog.w(this, "Can't change the max network thread count, because there "
                      + "are actively executing tasks in FileDownloader, please try again after all"
                      + " actively executing tasks are completed or invoking FileDownloader#pauseAll"
                      + " directly.");
              return false;
          }
  
          return FileDownloadServiceProxy.getImpl().setMaxNetworkThreadCount(count);
      }
docs: Set the maximum count of the network thread, what is the number of simultaneous downloads in
  FileDownloader.
  
  @param count the number of simultaneous downloads, scope: [1, 12].
  @return whether is successful to set the max network thread count.
  If there are any actively executing tasks in FileDownloader, you will receive a warn
  priority log int the logcat and this operation would be failed.