code: private byte[] getDigest(byte[] def, Configuration conf) {
      try {
        MessageDigest alg = MessageDigest.getInstance(conf.digestAlgorithm);
        return alg.digest(def);
      } catch (NoSuchAlgorithmException e) {
        throw new UnexpectedException(e);
      }
    }
docs: Gets the digest of the specified class definition.
  @param def The class definition.
  @param conf The application command line options.
  @return The digest of the class definition.