The type erasure is just a bad match with what's essentially a quite weak type system withq few other design flaws in it. Had the type system been good otherwise, it wouldn't have been that bad, but the way java works with for example array covariance and so on makes it a poor design.

That, and of course the fact that all AnyCollectionType<T> should work with primitive types without performance penalties. Having to use an MyFancyIntTree rather than MyFancyTeee<int> is a bloody disgrace.