@Override
public Set<Object> getSingletons() {
Set<Object> singletons = new HashSet<Object>();
singletons.add(new XopAttachmentServiceImpl());
singletons.add(new MultipartsServiceImpl());
JSONProvider provider = new JSONProvider();
// equivalent to provider.setIgnoreNamespaces(true);
provider.setOutTransformElements(
Collections.singletonMap("{http://books}Book", "Book"));