As described in Bug 1446, if we wish to generate one implementation extending another using Java callback functionality. The parsing of generics introduced here : 2abb40b0ca9a6a06bdbe3e66b4235301ed15c693 is incomplete (wildcard management is missing).
Created attachment 860 [details] Path of issue I've made a patch available here as patch (Or here : https://github.com/MathiusD/gluegen in 1447-java-wildcard-parsing branch)
Merged 33ffd1240a8d4f2cb4032ca2d111142e0f87beac Good stuff.