Java compiler bug with generics (opens in new tab)

Today I spent half a day debugging my code. I just completed a major redesign of a chunk of it thought I must have screwed something up badly. Well although I did screw it up, it was in a place where the compiler should have caught it.

Although the generics in java are better than not having anything, and they make my life a lot easier not needing to cast, they are still a bit buggy. Has anybody experienced something like this before, know what is causing this, and how to avoid this headache later? (see post for code)