Unsure we want to go this path. This snippet flows on the net for very long time, and is part of XStream acceptance tests, but it has drawbacks too.

Joerg describes on XStream user list the drawbacks on this approach (makes impossible use of implicit collections with XStream for example).
See related issues:
http://jira.codehaus.org/browse/XSTR-30
http://jira.codehaus.org/browse/XSTR-691

I'm rather to go with "compatible changes" on DTOs, as described in XStream FAQ. If not possible, introduce new resource with new DTOs instead of reworking old ones (especially if DTO use is shared across multiple resources).