in kafka-test/src/it/scala/org/apache/pekko/projection/kafka/integration/KafkaToSlickIntegrationSpec.scala [325:332]
def partitionForUser(userId: String): Int = {
userId match { // deterministically produce events across available partitions
case `user1` => 0
case `user2` => 1
case `user3` => 2
case `user4` => 3
}
}