11:57:45,320 AM [testsystem-pekko.actor.default-dispatcher-6] [INFO] RepointableActorRef -  pekkoDeadLetter Message [java.lang.String] from Actor[pekko://testsystem/system/testActor-13#1618758918] to Actor[pekko://testsystem/user/pingpongactor#-231217227] was not delivered. [1] dead letters encountered. If this is not an expected behavior then Actor[pekko://testsystem/user/pingpongactor#-231217227] may have terminated unexpectedly. This logging can be turned off or adjusted with configuration settings 'pekko.log-dead-letters' and 'pekko.log-dead-letters-during-shutdown'.
11:57:45,321 AM [testsystem-pekko.actor.default-dispatcher-6] [INFO] CoordinatedShutdown - Running CoordinatedShutdown with reason [ActorSystemTerminateReason]