Hi,
I am replacing replacing my legacy <https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#windowfunction-legacy> WindowFunction with AggregateFunction. I use TumblingEventTimeWindows, how can I get the start <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/windowing/windows/TimeWindow.html#getStart--> and end time?
