I have done numerous things using javassist but there is one thing I would really love to do and I have yet to find how so I'm hoping for some pointers. I would like to change methods return types from List to List. While I understand that this would not change the method bytecode (erasure technique), I'm doing that so that when using this code in a java 5 environment the programmer would be forced to use Lists of the given type. What i'm actually doing is from an XSD, i'm generating a model using JAXB 1. I'm then using javassist to instrument various behaviours into that JAXB model (like listeners, clone support and more) and generate a second "instrumented" model that i'm using for development. Any pointers on how to change the generic type of a return would be appreciated. Thanks View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4113548#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...