code: public void environmentStop(EnvironmentClassLoader loader)
    {
      Object obj = _objRef.get();
      if (obj == null)
        return;
      
      try {
        _preDestroy.invoke(obj, (Object []) null);
      } catch (Throwable e) {
        log.log(Level.WARNING, e.toString(), e);
      }
    }
docs: Handles the case where a class loader is dropped.