public class OAuth2AuthenticationReadConverter implements Converter<DBObject, OAuth2Authentication> {
@Override
public OAuth2Authentication convert(DBObject source) {
DBObject storedRequest = (DBObject)source.get("storedRequest");
OAuth2Request oAuth2Request = new OAuth2Request((Map<String, String>)storedRequest.get("requestParameters"),
(String)storedRequest.get("clientId"), null, true, new HashSet((List)storedRequest.get("scope")),
null, null, null, null);
DBObject userAuthorization = (DBObject)source.get("userAuthentication");
Object principal = getPrincipalObject(userAuthorization.get("principal"));