code: protected boolean isMagicCorrect(BufferedReader br) throws IOException {
          if (mCheckMagicSequence) {
              String magicLine = br.readLine();
              return (magicLine != null && magicLine.equals(mMode.getMagicSequence()));
          } else {
              return true;
          }
      }
docs: Check magic sequence. Note that subclasses are responsible to decide if
  something should be read from buffer. This approach was taken to support
  old format without magic sequence.