code: public void add(String line) {
          String[] parsed = line.split(":");
          final String name = parsed[0].trim();
          final String value = parsed[1].trim();
  
          add(name, value);
      }
docs: We have already handled etag, and will add 'If-Match' & 'Range' value if it works.
  
  @see com.liulishuo.filedownloader.download.ConnectTask#addUserRequiredHeader