docs: protected void moveValue(int step) {
  
          Element e = getElement();
          Element parent = e.getParent();
          List<Element> siblings = CmsXmlGenericWrapper.elements(parent);
          int idx = siblings.indexOf(e);
          int newIdx = idx + step;
          siblings.remove(idx);
          siblings.add(newIdx, e);
          m_index += step;
      }