xstream.registerConverter(new UserRightIdSingleValueConverter(), 20);
xstream.registerConverter(new UserPrefAreaSingleValueConverter(), 19);
// alle Objekte Laden und speichern
xstream.fromXML(reader);
xstreamSavingConverter.saveObjects();
} catch (final Exception ex) {
log.error(ex.getMessage(), ex);
throw new RuntimeException(ex);
} finally {
IOUtils.closeQuietly(reader);