I\'m following the instructions on using xsi:type from this oft-cited blog post:
http://blog.bdoughan.com/2010/11/jaxb-and-inheritance-using-xsitype.html
Bas
In your test case you need to specify that the DocumentBuilderFactory is namespace aware. Without this setting the DOM input to your JAXB implemenation won't contain a properly formed xsi:type attribute.
DocumentBuilderFactory
xsi:type
documentBuilderFactory.setNamespaceAware(true);