private final JAXBContext context;
public Consumer(Callback callback, String address, Class<?> ... extraClasses) {
this.callback = callback;
WSNHelper helper = WSNHelper.getInstance();
if (helper.supportsExtraClasses()) {
this.endpoint = helper.publish(address, this, extraClasses);
this.context = null;
} else {
this.endpoint = helper.publish(address, this);
if (extraClasses != null && extraClasses.length > 0) {