docs: private Entity parseResourceRef(final EntitySet set, final Node n) throws ResourceXMLParserException {
          final Node node2 = n.selectSingleNode("@" + COMMON_NAME);
          if (null == node2) {
              throw new ResourceXMLParserException("@" + COMMON_NAME + " required: " + reportNodeErrorLocation(n));
          }
          final String rname = node2.getStringValue();
          return set.getOrCreateEntity( rname);
      }