* Replace MaterializerSettings with Attributes #25559
* Field access to settings deprecated to make stages use attributes instead
* Internal stages updated to use attributes
* Docs on ActorMaterializerSettings updated to recommend away from using it
* Verify all stages stopped after each testcase in FlowGroupBySpec
* Subscription timeout attributes merged into one
Introduces a materializer started through an extension and then an implicit
conversion for Scala turning an implicitly available ActorSystem into a
materializer. The Java APIs has been ammended with run-methods accepting
an ActorSystem.
* previous `schedule` method is trying to maintain a fixed average frequency
over time, but that can result in undesired bursts of scheduled tasks after a long
GC or if the JVM process has been suspended, same with all other periodic
scheduled message sending via various Timer APIs
* most of the time "fixed delay" is more desirable
* we can't just change because it's too big behavioral change and some might
depend on previous behavior
* deprecate the old `schedule` and introduce new `scheduleWithFixedDelay`
and `scheduleAtFixedRate`, when fixing the deprecation warning users should
make a concious decision of which behavior to use (scheduleWithFixedDelay in
most cases)
* Streams
* SchedulerSpec
* test both fixed delay and fixed rate
* TimerSpec
* FSM and PersistentFSM
* mima
* runnable as second parameter list, also in typed.Scheduler
* IllegalStateException vs SchedulerException
* deprecated annotations
* api and reference docs, all places
* migration guide
* Implements actorRef source variant with backpressure #17610
* Small improvements to documentation and source #17610
* Small improvements to test #17610
* Small improvements to implementation and tests #17610
* Adds API for akka-typed #17610
* Adds ack sender and java api for typed #17610
* Adds internal access to materializer before initialization (#25324)
* Implements new actorRef source based on graph stage (#25324)
* Removes obsolete actorRef source (#25324)
* Improves backwards compatibility with old implementation (#25324)
* Removes dedicated new subclass for materializer access again (#25324)
* Improves implementation (#25324)
* Finalizes implementation (#25324)
* Small improvements to API and documentation (#25324)
* Completion strategy as a replacement for poison pill (#25324)
* Adding more tests and updating the documentation (#25324)
* ⇒, →, ←
* because we don't want to show them in documentation snippets and
then it's complicated to avoid that when snippets are
located in src/test/scala in individual modules
* dont replace object `→` in FSM.scala and PersistentFSM.scala
