Hi all:
Currently, The "TwoInputStreamOperator" such as
"CoBroadcastWithKeyedOperator" "KeyedCoProcessOperator" and the
(Co)stream such as "ConnectedStreams" "BroadcastConnectedStream" only
support compute watermark by two stream.
but we just need one stream to compute watermark in some case.
For example: one stream is only rule data or control command, it
don't hava event time.
I think user has right to choose which stream to compute watermark.Best Ocean
