When using XStreamMarshaller, I get following error
XStream marshalling ended with exception org.springframework.oxm.MarshallingFailureException: XStream marshalling exception;
nested exception is com.thoughtworks.xstream.converters.ConversionException: No converter specified for class springtest.xmlmarshalling.Data
After some debugging, I think the problem is that XStreamMarshaller's converterRegistry field is not initialized (it remains NULL, unlike the converterLookup field just a line above) and when the XStream object is being created in constructXStream() method, the NULL value causes that no converter is registered.
Let me know if you need more details or example war to reproduce this.