Is there an example/docs on how to evict state from a window?
http://www.onyxplatform.org/docs/cheat-sheet/latest/#trigger-entry/:trigger/post-evictor is probably what you want. The best description is in http://www.onyxplatform.org/docs/cheat-sheet/latest/#trigger-entry/:trigger/refinement
If using grouping, I assume "window state" refers to the state for a particular group value?
window (e.g. time window) as well as everything relating to a group key, if all of the windows for that group key have been evicted