Fix CME when getting while computing

[HSGamer]

No description provided.

[tastybento]

Can you share the error you were getting before the fix?

What triggered the error?

[HSGamer]

It's a rare case when a placeholder try to get the likes asynchronously.
I missed the stacktrace so I don't have the details.
I remember this line tell the issue
Since it's rarely to happen, I think we can close this pull request until I get the issue.

[HSGamer]

This is the log that tells the exception

[10:02:53] [Craft Scheduler Thread - 13/WARN]: [SimpleBoard] Plugin SimpleBoard v1.0-SNAPSHOT generated an exception while executing task 614
java.util.ConcurrentModificationException: null
	at java.util.HashMap.computeIfAbsent(HashMap.java:1226) ~[?:?]
	at world.bentobox.likes.managers.LikesManager.load(LikesManager.java:152) ~[?:?]
	at world.bentobox.likes.managers.LikesManager.newPlayer(LikesManager.java:233) ~[?:?]
	at world.bentobox.likes.managers.LikesManager.getIslandLikes(LikesManager.java:220) ~[?:?]
	at world.bentobox.likes.managers.LikesManager.getIslandLikes(LikesManager.java:261) ~[?:?]
	at world.bentobox.likes.placeholders.LikesAddonPlaceholderType.getObject(LikesAddonPlaceholderType.java:1445) ~[?:?]
	at world.bentobox.likes.placeholders.LikesAddonPlaceholderType.lambda$static$0(LikesAddonPlaceholderType.java:33) ~[?:?]
	at world.bentobox.likes.placeholders.LikesAddonPlaceholderType$$Lambda$5528/00000000DDDD7770.onReplace(Unknown Source) ~[?:?]
	at world.bentobox.likes.placeholders.LikesAddonPlaceholder.onReplace(LikesAddonPlaceholder.java:52) ~[?:?]
	at world.bentobox.bentobox.api.placeholders.placeholderapi.BasicPlaceholderExpansion.onPlaceholderRequest(BasicPlaceholderExpansion.java:47) ~[?:?]
	at world.bentobox.bentobox.api.placeholders.placeholderapi.AddonPlaceholderExpansion.onPlaceholderRequest(AddonPlaceholderExpansion.java:5) ~[?:?]
	at me.clip.placeholderapi.PlaceholderHook.onRequest(PlaceholderHook.java:31) ~[?:?]
	at me.clip.placeholderapi.replacer.CharsReplacer.apply(CharsReplacer.java:156) ~[?:?]
	at me.clip.placeholderapi.PlaceholderAPI.setPlaceholders(PlaceholderAPI.java:69) ~[?:?]
	at me.hsgamer.simpleboard.Utils.replacePlaceholders(Utils.java:26) ~[?:?]
	at me.hsgamer.simpleboard.Utils.format(Utils.java:16) ~[?:?]
	at me.hsgamer.simpleboard.Board.lambda$update$0(Board.java:24) ~[?:?]
	at me.hsgamer.simpleboard.Board$$Lambda$6273/000000005012E410.apply(Unknown Source) ~[?:?]
	at java.util.ArrayList.replaceAllRange(ArrayList.java:1712) ~[?:?]
	at java.util.ArrayList.replaceAll(ArrayList.java:1702) ~[?:?]
	at me.hsgamer.simpleboard.Board.update(Board.java:24) ~[?:?]
	at me.hsgamer.simpleboard.Board$$Lambda$6155/00000000DDFD0540.run(Unknown Source) ~[?:?]
	at org.bukkit.craftbukkit.v1_16_R3.scheduler.CraftTask.run(CraftTask.java:100) ~[server-patched.jar:git-Paper-469]
	at org.bukkit.craftbukkit.v1_16_R3.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:54) ~[server-patched.jar:git-Paper-469]
	at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) ~[server-patched.jar:git-Paper-469]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) [?:?]
	at java.lang.Thread.run(Thread.java:851) [?:?]

[BONNe]

I am currently thinking of applying merge or fixing placeholder code.
I implemented it in lazy way, so it is less lines of code, and did not check if that is correct.

tasty, what do you think, apply merge or fix an issue in other parts?

[tastybento]

I don't think there is a obligation for us to support async placeholder requests, but this PR is not a big change - just changing to concurrent hashmap. So, I think it should be fine to merge this PR and then work on other items. I'll let you decide @BONNe.

[BONNe]

Thanks for your fix @HSGamer