code: public static String encodeHighLevel(String msg) {
      return encodeHighLevel(msg, SymbolShapeHint.FORCE_NONE, null, null);
    }
docs: Performs message encoding of a DataMatrix message using the algorithm described in annex P
  of ISO/IEC 16022:2000(E).
  
  @param msg the message
  @return the encoded message (the char values range from 0 to 255)