There should be an xmlns:test
attribute in your XML document if there is an test
prefix used. Without that attribute declaring the prefix you should remove the prefix from your document for it to be valid.
UPDATE
I do not control the document so I guess I'll have to find some workaround for removing the test: prefix and xsi: before unmarshalling.
Below is a link to an example that should help you build what you are looking for. It leverages JAXB's UnmarshallerHandler
with a SAX parser to treat the prefix as parent of the element name.