Bug Folia Join Event

[Euphillya]

Fix : use ConcurrentHashMap

[17:16:35 ERROR]: Could not pass event PlayerJoinEvent to mcMMO v2.2.018
java.util.ConcurrentModificationException: null
        at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1229) ~[?:?]
        at mcMMO.jar/com.gmail.nossr50.locale.LocaleLoader.getString(LocaleLoader.java:52) ~[mcMMO.jar:?]
        at mcMMO.jar/com.gmail.nossr50.util.Motd.displayVersion(Motd.java:36) ~[mcMMO.jar:?]
        at mcMMO.jar/com.gmail.nossr50.util.Motd.displayAll(Motd.java:19) ~[mcMMO.jar:?]
        at mcMMO.jar/com.gmail.nossr50.listeners.PlayerListener.onPlayerJoin(PlayerListener.java:580) ~[mcMMO.jar:?]
        at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor239.execute(Unknown Source) ~[?:?]
        at org.bukkit.plugin.EventExecutor$2.execute(EventExecutor.java:77) ~[paper-mojangapi-1.21.1-R0.1-SNAPSHOT.jar:?]
        at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80) ~[paper-mojangapi-1.21.1-R0.1-SNAPSHOT.jar:1.21.1-26-b440e32]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[paper-mojangapi-1.21.1-R0.1-SNAPSHOT.jar:?]
        at io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:54) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.callEvent(PaperPluginManagerImpl.java:131) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:628) ~[paper-mojangapi-1.21.1-R0.1-SNAPSHOT.jar:?]
        at net.minecraft.server.players.PlayerList.placeNewPlayer(PlayerList.java:440) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at net.minecraft.server.network.ServerConfigurationPacketListenerImpl.lambda$handleConfigurationFinished$2(ServerConfigurationPacketListenerImpl.java:203) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$PrioritisedQueue$ChunkBasedPriorityTask.executeInternal(RegionizedTaskQueue.java:499) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$PrioritisedQueue.executeTask(RegionizedTaskQueue.java:429) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at io.papermc.paper.threadedregions.RegionizedTaskQueue$RegionTaskQueueData.drainTasks(RegionizedTaskQueue.java:258) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1696) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at io.papermc.paper.threadedregions.TickRegions$ConcreteRegionTickHandle.tickRegion(TickRegions.java:407) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at io.papermc.paper.threadedregions.TickRegionScheduler$RegionScheduleHandle.runTick(TickRegionScheduler.java:418) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at ca.spottedleaf.concurrentutil.scheduler.SchedulerThreadPool$TickThreadRunner.run(SchedulerThreadPool.java:540) ~[bloomexcalia-1.21.1.jar:1.21.1-26-b440e32]
        at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]