Flink connectedstreams

https://stackoverflow.com/questions/40613684/apache-flink-scope-of-valuestate-in-connectedstreams

https://stackoverflow.com/questions/33755697/flink-sharing-state-in-coflatmapfunction

https://stackoverflow.com/questions/40553744/flink-streaming-from-one-window-lookup-state-in-another-window

http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/ConnectedStream-keyby-issues-td12999.html