10:21:09,104 AM [testsystem-pekko.actor.default-dispatcher-5] [INFO] RepointableActorRef -  pekkoDeadLetter Message [java.lang.String] from Actor[pekko://testsystem/system/testActor-13#-1961457724] to Actor[pekko://testsystem/user/pingpongactor#716926919] was not delivered. [1] dead letters encountered. If this is not an expected behavior then Actor[pekko://testsystem/user/pingpongactor#716926919] 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'.
10:21:09,107 AM [testsystem-pekko.actor.default-dispatcher-5] [INFO] CoordinatedShutdown - Running CoordinatedShutdown with reason [ActorSystemTerminateReason]