// use plain JDK Object(Input|Output)Stream
WicketObjects.setObjectStreamFactory(new GaeObjectStreamFactory());
// save older version of pages in the HttpSession
final DataStoreEvictionStrategy evictionStrategy;
if (application instanceof GaeApplication) {
evictionStrategy = ((GaeApplication)application).getEvictionStrategy();
} else {
evictionStrategy = new PageNumberEvictionStrategy(10);
}