code: protected String getMessage(Message message) {
      switch(message) {
        case CHECK:
          return "This conversion doesn't seem right. Do you want to correct it automatically?";
        case SUGGESTION:
          return "Writing for an international audience? Consider adding the metric equivalent.";
        case CHECK_UNKNOWN_UNIT:
          return "This conversion doesn't seem right, unable to recognize the used unit.";
        case UNIT_MISMATCH:
          return "These units don't seem to be compatible.";
        default:
          throw new RuntimeException("Unknown message type: " + message);
      }
    }
docs: Override in subclasses