WindowedStreamPartitioner is a StreamPartitioner of Windowed keys (and V values).
WindowedStreamPartitioner is used as the default StreamPartitioner when WindowedSerializer is used for record keys.
WindowedStreamPartitioner is created exclusively when StreamSinkNode is requested to writeToTopology.
WindowedStreamPartitioner takes a WindowedSerializer when created.
When requested to determine the partition for a record, WindowedStreamPartitioner requests the WindowedSerializer to serializeBaseKey (for the given topic and windowedKey). It then generates 32-bit murmur2 hash from the byte array and chooses the partition.