code: void addWab(WAB wab, WABInstaller installer) {
          if (!Thread.holdsLock(this)) {
              throw new IllegalStateException();
          }
          if (wabs == null) {
              wabs = new ConcurrentLinkedQueue<WAB>();
          }
          wabs.add(wab);
  
          //if the group is uninstalled, this is a late wab addition, so clean it up.
          if (groupUninstalled)
              uninstallGroup(installer);
      }
docs: after adding the wab to the web container etc..