ConcurrentModificationException when saving attribute data under certain conditions

[WiIIiam278]

This seems to be safe to ignore, though. Basically it seems like Minecraft is trying to do stuff with attributes while we're trying to read it.

Stack trace

java.util.ConcurrentModificationException: null
        at java.util.HashMap.computeIfAbsent(HashMap.java:1221) ~[?:?]
        at net.minecraft.world.entity.ai.attributes.AttributeMap.m_22146_(AttributeMap.java:49) ~[server-1.20.2-20230921.100330-srg.jar%23186!/:?]
        at org.bukkit.craftbukkit.v1_20_R2.attribute.CraftAttributeMap.getAttribute(CraftAttributeMap.java:19) ~[forge-1.20.2-48.1.0-universal.jar%23191!/:?]
        at org.bukkit.craftbukkit.v1_20_R2.entity.CraftLivingEntity.getAttribute(CraftLivingEntity.java:640) ~[forge-1.20.2-48.1.0-universal.jar%23191!/:?]
        at net.william278.husksync.data.BukkitData$Attributes.lambda$adapt$0(BukkitData.java:571) ~[?:?]
        at java.lang.Iterable.forEach(Iterable.java:75) ~[?:?]
        at net.william278.husksync.data.BukkitData$Attributes.adapt(BukkitData.java:570) ~[?:?]
        at net.william278.husksync.data.BukkitUserDataHolder.getAttributes(BukkitUserDataHolder.java:124) ~[?:?]
        at net.william278.husksync.data.BukkitUserDataHolder.getData(BukkitUserDataHolder.java:44) ~[?:?]
        at net.william278.husksync.data.UserDataHolder.lambda$getData$1(UserDataHolder.java:47) ~[?:?]
        at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[?:?]
        at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[?:?]
        at java.util.Iterator.forEachRemaining(Iterator.java:133) ~[?:?]
        at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1845) ~[?:?]
        at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[?:?]
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[?:?]
        at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921) ~[?:?]
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?]
        at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:693) ~[?:?]
        at net.william278.husksync.data.UserDataHolder.getData(UserDataHolder.java:49) ~[?:?]
        at net.william278.husksync.data.UserDataHolder.createSnapshot(UserDataHolder.java:75) ~[?:?]
        at net.william278.husksync.listener.EventListener.lambda$saveOnWorldSave$1(EventListener.java:84) ~[?:?]
        at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[?:?]
        at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[?:?]
        at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) ~[?:?]
        at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[?:?]
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[?:?]
        at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[?:?]
        at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[?:?]
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?]
        at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[?:?]
        at net.william278.husksync.listener.EventListener.saveOnWorldSave(EventListener.java:83) ~[?:?]
        at net.william278.husksync.listener.BukkitEventListener.lambda$onWorldSave$1(BukkitEventListener.java:112) ~[?:?]
        at org.bukkit.craftbukkit.v1_20_R2.scheduler.CraftTask.run(CraftTask.java:77) ~[forge-1.20.2-48.1.0-universal.jar%23191!/:?]
        at org.bukkit.craftbukkit.v1_20_R2.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:54) [forge-1.20.2-48.1.0-universal.jar%23191!/:?]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) [?:?]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) [?:?]
        at java.lang.Thread.run(Thread.java:840) [?:?]