private boolean isVersionableClass(RegistryObjectType ro) {
    boolean isVersionable = false;

    // System.err.println("isVersionable entered. ro=" + ro.getClass().getName());
    Iterator iter = versionableClassNameSet.iterator();
    while (iter.hasNext()) {
      Class clazz = (Class) iter.next();
      // System.err.println("    isVersionable clazz=" + clazz.getName() + " isAssignableFrom = " +
      // clazz.isAssignableFrom(ro.getClass()));
      if (clazz.isAssignableFrom(ro.getClass())) {
        isVersionable = true;
        break;
      }
    }
    return isVersionable;
  }