Little race-condition in config-reload

[ggrandes]

2020-07-11T21:13:18 [INFO] [Jrinetd] [ConfigWatcher] Reloaded config
2020-07-11T21:13:18 [INFO] [80004d4f] [events-19791-127.0.0.1:2222] Ending handler on 127.0.0.1:2222
2020-07-11T21:13:18 [ERROR] [80004d4e] [events-19790-127.0.0.1:2222] Unhandled Exception: java.util.ConcurrentModificationException
java.util.ConcurrentModificationException
        at java.base/java.util.HashMap$HashIterator.remove(HashMap.java:1507)
        at org.javastack.jrinetd.ServerEventHandler.process(ServerEventHandler.java:125)
        at org.javastack.jrinetd.ServerEventHandler.run(ServerEventHandler.java:135)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:834)
2020-07-11T21:13:18 [INFO] [80004d4e] [events-19790-127.0.0.1:2222] Ending handler on 127.0.0.1:2222