Generating hashCode() and equals() when creating Java classes using Mojo Jaxb2 maven plugin

The code I'm working on is using jaxb2-maven-plugin from org.codehaus.mojo to generate Java classes from XSD schema. I'm looking for a way to automatically implement equals() and hashCode() methods for those classes, but it seems there is not a way. I know that there are other JAXB2 Maven plugins that do that (http://confluence.highsource.org/display/J2B/Home for example), but I was wondering if anyone of you encountered this issue before and if there's a way for fixing it. I'm generating the classes using the xjc goal.