code: public void readBatteryLevel(final Callback<BatteryLevel> callback) {
          gattClient.getBatteryProfile().getBatteryLevel(new BatteryLevelCallback() {
              @Override
              public void onBatteryLevel(int percentage) {
                  callback.onResult(new BatteryLevel(percentage));
              }
          });
      }
docs: Read the battery level.
  
  @param callback the callback for the {@link com.punchthrough.bean.sdk.message.BatteryLevel}
  result