private final Map<String, JavascriptAddOnFactory> javascriptAddOnFactories = new HashMap<String, JavascriptAddOnFactory>();
public UIBuilder() {
History.addValueChangeHandler(this);
final AddonList addonList = GWT.create(PonyAddonList.class);
final List<AddonFactory> addonFactoryList = addonList.getAddonFactoryList();
for (final AddonFactory addonFactory : addonFactoryList) {
addonByKey.put(addonFactory.getSignature(), addonFactory);
}