I've been using
package com.sun.xml.internal.bind.marshaller does not exist
I don't think that the class
com.sun.xml.internal.bind.marshaller.NamespacePrefixMapper is a replacement of
com.sun.xml.bind.marshaller.NamespacePrefixMapper, the former is there for a long time and it NOT MEANT TO BE USED BY YOU AT ALL (hence the
The problem here is that JavaSE 6 doesn't have the JAXB RI (it has a JAXB implemenation but not JAXB RI) so if you want to rely on RI specific feature, you should bundle JAXB RI in your application (and that would protect you from JAXB changes in Java SE).