code: final JsMsgMap getJmsUserPropertyMap() {
          if (jmsUserPropertyMap == null) {
              List<String> keys = (List<String>) getApi().getField(JsApiAccess.JMSPROPERTY_NAME);
              List<Object> values = (List<Object>) getApi().getField(JsApiAccess.JMSPROPERTY_VALUE);
              jmsUserPropertyMap = new JsMsgMap(keys, values);
          }
          return jmsUserPropertyMap;
      }
docs: Helper method used by the main Message Property methods to obtain the
  JMS-valid Property items in the form of a map.
  <p>
  The method has package level visibility as it is used by JsJmsMessageImpl
  and JsSdoMessageimpl.
  
  @return A JsMsgMap containing the Message Property name-value pairs.