The Kafka Streams documentation discussed how to assign timestamps to records received from source topic via TimestampExtractor. But neither the Kafka nor the Confluent documentation on Kafka Streams explain what timestamp is associated with a record that has been transformed.
What timestamp is associated with records that are output by stateless transformations like map or flatMap? What timestamp is associated with records that are outputted by stageful transformations like aggregations or joins? What about transformations on windows? What timestamp does the Kafka publisher use, if any, when writing to an intermediate topic via through() or a sink via to()?
