This project shows how to write a KStreams application to create new records from a single message using flatmap
make clusterDebug the App.java class.
kafka-console-producer --broker-list localhost:9092 --topic foo
> [{"a": "asdf" },{"a": "qwer"}]
> [{"a": "asdf" },{"a": "qwer"}]
Go to http://localhost:9021 under topics and view the foo topic. You should see these messages broken out into multple records.