The PR for this has a question that I'd like some feedback on. https://github.com/apache/flink/pull/5295
The issue is, in order to be able to pass a typed event to the session gap extractor, the assigner needs to be generic. And if the assigner is generic, then the triggers need to be generic. And unfortunately, the two current triggers aren't generic, and I've need to add exact copies of these triggers that do accept a type. It's possible to remove all the typing (and therefore the two new triggers), and use the current triggers, but that causes the extract method in the SessionWindowTimeGapExtractor to accept Object, and anyone implementing it will need to cast the event to their expected type. I don't find making the end user cast from Object to be the most friendly interface, especially when the type information is otherwise available, but I'm also not happy to have created exact copies of the trigger classes simply because they aren't currently generic. Was a similar discussion had when the current Session Window Assigners were implemented? They hard type the event to Object as well, which I found a bit odd. Thanks, Dyana
