code: public Iterable<String> getMemberNames() {
          if (m_childNodeMap == null) {
              m_childNodeMap = new LinkedHashMap<String, UNode>();
          }
          return m_childNodeMap.keySet();
      }
docs: Get the member (child) names of this UNode, if any, as an Iterable String object.
  If this UNode is not a MAP or has no children, there will be no child names.
  
  @return  An Iterable String object that returns this node's member names if it is
  a map. The result won't be null but there may not be any child members.