in cassandra/src/it/scala/org/apache/pekko/projection/cassandra/CassandraProjectionSpec.scala [590:605]
override def process(group: immutable.Seq[Envelope]): Future[Done] = {
val newState = state.flatMap { s =>
val concatStr = group.foldLeft(s) {
case (None, env) => Some(ConcatStr(env.id, env.message))
case (Some(acc), env) => Some(acc.concat(env.message))
}
val ok = concatStr match {
case Some(c) => repository.save(c)
case None => Future.successful(Done)
}
ok.map(_ => concatStr)
}
state = newState
newState.map(_ => Done)
}