As you can tell, I am running a server using "Yatopia" which is a fork of paper that includes many optimization patches, of their own, and many taken from other repos like Purpur and EMC. I'm sure this may cause issues with some plugins but so far I have had none, however I think this issue has yatopia to blame, they use a custom optimized linked hash set object.
[02:44:35 ERROR]: Could not pass event CreatureSpawnEvent to Vivecraft-Spigot-Extensions v1.16.3-r1
java.lang.ClassCastException: it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet cannot be cast to java.util.LinkedHashSet
at org.vivecraft.VSE.EditEntity(VSE.java:322) ~[?:?]
at org.vivecraft.VSE.onEvent(VSE.java:305) ~[?:?]
at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor230.execute(Unknown Source) ~[?:?]
at org.bukkit.plugin.EventExecutor.lambda$create$1(EventExecutor.java:69) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:607) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at org.bukkit.craftbukkit.v1_16_R2.event.CraftEventFactory.callCreatureSpawnEvent(CraftEventFactory.java:673) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at org.bukkit.craftbukkit.v1_16_R2.event.CraftEventFactory.doEntityAddEventCalling(CraftEventFactory.java:594) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.WorldServer.addEntity0(WorldServer.java:1678) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.WorldServer.addEntity(WorldServer.java:1579) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.WorldAccess.lambda$addAllEntities$0(WorldAccess.java:13) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:419) ~[?:1.8.0_242]
at java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:742) ~[?:1.8.0_242]
at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:647) ~[?:1.8.0_242]
at net.minecraft.server.v1_16_R2.WorldAccess.addAllEntities(WorldAccess.java:13) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.SpawnerCreature.spawnMobsInternal(SpawnerCreature.java:261) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.SpawnerCreature.spawnMobs(SpawnerCreature.java:187) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.SpawnerCreature.a(SpawnerCreature.java:158) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.ChunkProviderServer.tickChunks(ChunkProviderServer.java:1030) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.ChunkProviderServer.tick(ChunkProviderServer.java:926) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.WorldServer.doTick(WorldServer.java:887) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.MinecraftServer.b(MinecraftServer.java:1434) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.DedicatedServer.b(DedicatedServer.java:390) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.MinecraftServer.a(MinecraftServer.java:1282) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.MinecraftServer.w(MinecraftServer.java:1007) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at net.minecraft.server.v1_16_R2.MinecraftServer.lambda$a$0(MinecraftServer.java:165) ~[patched_1.16.3.jar:git-Yatopia-"0faeed7"]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_242]```
Hello!
As you can tell, I am running a server using "Yatopia" which is a fork of paper that includes many optimization patches, of their own, and many taken from other repos like Purpur and EMC. I'm sure this may cause issues with some plugins but so far I have had none, however I think this issue has yatopia to blame, they use a custom optimized linked hash set object.