code: @Override
      protected void checkForSessionIdListenerAndAdd(Object listener){
          // Added for Servlet 3.1 support
          if (isHttpSessionIdListener(listener)) {
              // add to the HttpSessionIdListener list
              ((IHttpSessionContext31)this.sessionCtx).addHttpSessionIdListener((javax.servlet.http.HttpSessionIdListener) listener, name);
              this.sessionIdListeners.add(listener);
          }
      }
docs: /*
  (non-Javadoc)
  The is called from loadLifecycleListeners
  @see com.ibm.ws.webcontainer.osgi.webapp.WebApp#checkForSessionIdListenerAndAdd(java.lang.Object)