code: public static String getStaticNodeId(String nodeId) {
          String application = NodeIdBean.parse(nodeId).getApplication();
          if (nodeId_to_StaticFinalId_map.get(nodeId) == null) {
              Instance<NodeStatus> instance = ApplicationDiscovery.singleton.instance(nodeId);
              if (instance != null) {
                  LOG.debug("Instance with given nodeId is found online, then initialize its static node id and put it into the map.");
                  onEvent(nodeId);
              } else {
                  LOG.warn(new IllegalArgumentException("Bad node id or the node is offline: " + nodeId));
              }
          }
          return nodeId_to_StaticFinalId_map.get(nodeId) == null ?
                  application + NodeIdBean.splitter + "null" ://it represents a none exited static id.
                  application + NodeIdBean.splitter + nodeId_to_StaticFinalId_map.get(nodeId);
      }
docs: Lasy-create staticNodeId for the given node id.
  
  @param nodeId the node id generated by the node itself.
  @return the staticNodeId eg. payment---0