In the documentation <https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#allowed-lateness> it states that:
*[…], Flink keeps the state of windows until their allowed lateness expires. Once this happens, Flink removes the window and deletes its state, as also described in the Window Lifecycle <https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#window-lifecycle> section.* However, something doesn't make sense to me. If Flink deletes the window state, then how can it know that subsequent events are late? i.e. if the state is deleted, then Flink has no way of knowing than an event is late, because it can think it's just a new event, unless it keeps track of which keyed windows are closed forever. Does Flink remember which keyed windows are closed forever? Thanks.
