[Bug]: AssignContext for window mapping fn is missing source window when using side inputs

[alexmalao1]

What happened?

When using default_window_mapping_fn in sideinputs.py for mapping windows, the target window fn is given an AssignContext that is missing the source window.

For all timestamp based windows functions, this is not an issue because the window function uses the timestamp. For any custom non-timed based window functions, the windowing function should require the source window.

See

beam/sdks/python/apache_beam/transforms/sideinputs.py

Line 60 in a57872f

def map_via_end(source_window: window.BoundedWindow) -> window.BoundedWindow:

Issue Priority

Priority: 2 (default / most bugs should be filed as P2)

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[alexmalao1]

cc: @hjtran

[alexmalao1]

.take-issue