错误信息如下：
[INFO] [akkaDeadLetter][04/05/2022 00:02:44.179] [client-akka.actor.default-dispatcher-7] [akka://client/deadLetters] Message [com.m24.learn.akka.yellowchicken.common.ClientMessage] from Actor[akka://client/user/CustomerActor#-724440308] to Actor[akka://client/deadLetters] was not delivered. [1] dead letters encountered. If this is not an expected behavior then Actor[akka://client/deadLetters] may have terminated unexpectedly. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.
原因是初始化字符串空格中存在问题
修改前字符串如下：
修改后：
