THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
...
Motivation
In DataStream API, a non-keyed DataStream can be transformed into a KeyedStream through keyBy, and then further transformed into a WindowedStream through window operations. WindowedStream enables window processing on records with the same key. With the improvement of FLIP-331, WindowedStream will support the full window processing by the window assigner EndOfStreamWindows for which the which the window is only triggered at the end of inputs.
...