code: protected String properties(TQProperty<?>... props) {
      StringBuilder selectProps = new StringBuilder(50);
      for (int i = 0; i < props.length; i++) {
        if (i > 0) {
          selectProps.append(",");
        }
        selectProps.append(props[i].propertyName());
      }
      return selectProps.toString();
    }
docs: Append the properties as a comma delimited string.