docs: public static String serializeMetaData(Map<String, List<String>> metaData) {
          StringBuilder buf = new StringBuilder();
          if (metaData != null && metaData.size() > 0) {
              buf.append("<metadata xmlns=\"http://jivesoftware.com/protocol/workgroup\">");
              for (String key : metaData.keySet()) {
                  List<String> value = metaData.get(key);
                  for (String v : value) {
                      buf.append("<value name=\"").append(key).append("\">");
                      buf.append(StringUtils.escapeForXmlText(v));
                      buf.append("</value>");
                  }
              }
              buf.append("</metadata>");
          }
          return buf.toString();
      }