code: public JSONArray construct(){
          JSONArray ret = new JSONArray();
          ret.put(start.getMillis() / 1000);
          ret.put(end.getMillis() / 1000);
          ret.put(runtime);
          ret.put(area);
          ret.put(0);
          ret.put(completed ? 1 : 0);
          return ret;
      }
docs: Construct the message the vacuum sends to the controlling device.
  @return The constructed message.