Yesterday at a seminar the presenter showed a small java program, with 3 classes, featuring both co-variance and contra-variance. When attempting to compile using javac, the type checker will throw a StackOverflowException.
The snippet is developed by some guys that work at Microsoft (think one was called Kennedy).
Can't find it using Google. Does anyone know the code snippet, and could you paste it here (it's max. 10 lines of code), for everyone to see? :)
It was quite fun...