Stack Trace:
java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @66f2d70
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:357)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:199)
at java.base/java.lang.reflect.Method.setAccessible(Method.java:193)
at com.comphenix.protocol.reflect.compiler.StructureCompiler.generateClass(StructureCompiler.java:299)
at com.comphenix.protocol.reflect.compiler.StructureCompiler.compile(StructureCompiler.java:213)
at com.comphenix.protocol.reflect.compiler.BackgroundCompiler$2.call(BackgroundCompiler.java:204)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:831)
Dump:
Parameters:
com.comphenix.protocol.reflect.StructureModifier@3d389684[
targetType=class net.minecraft.server.v1_16_R3.PacketPlayOutChat
target=
converter=
fieldType=class java.lang.Object
data=[private net.minecraft.server.v1_16_R3.IChatBaseComponent net.minecraft.server.v1_16_R3.PacketPlayOutChat.a, public net.kyori.adventure.text.Component net.minecraft.server.v1_16_R3.PacketPlayOutChat.adventure$message, public net.md_5.bungee.api.chat.BaseComponent[] net.minecraft.server.v1_16_R3.PacketPlayOutChat.components, private net.minecraft.server.v1_16_R3.ChatMessageType net.minecraft.server.v1_16_R3.PacketPlayOutChat.b, private java.util.UUID net.minecraft.server.v1_16_R3.PacketPlayOutChat.c]
defaultFields={public net.md_5.bungee.api.chat.BaseComponent[] net.minecraft.server.v1_16_R3.PacketPlayOutChat.components=2, private net.minecraft.server.v1_16_R3.ChatMessageType net.minecraft.server.v1_16_R3.PacketPlayOutChat.b=3, private java.util.UUID net.minecraft.server.v1_16_R3.PacketPlayOutChat.c=4}
subtypeCache={class net.minecraft.server.v1_16_R3.ChatMessageType=StructureModifier[fieldType=class net.minecraft.server.v1_16_R3.ChatMessageType, data=[private net.minecraft.server.v1_16_R3.ChatMessageType net.minecraft.server.v1_16_R3.PacketPlayOutChat.b]], class java.util.UUID=StructureModifier[fieldType=class java.util.UUID, data=[private java.util.UUID net.minecraft.server.v1_16_R3.PacketPlayOutChat.c]], interface net.minecraft.server.v1_16_R3.IChatBaseComponent=StructureModifier[fieldType=interface net.minecraft.server.v1_16_R3.IChatBaseComponent, data=[private net.minecraft.server.v1_16_R3.IChatBaseComponent net.minecraft.server.v1_16_R3.PacketPlayOutChat.a]]}
customConvertHandling=false
useStructureCompiler=true
]
manager:
com.comphenix.protocol.injector.PacketFilterManager@6dd72e73[
unhookTask=com.comphenix.protocol.injector.DelayedSingleTask@713f194
packetListeners=[PacketAdapter[plugin=VotingPlugin, sending=EMPTY_WHITELIST, receiving=ListeningWhitelist[priority=NORMAL, packets=[UPDATE_SIGN[class=PacketPlayInUpdateSign, id=43]], gamephase=PLAYING, options=[]]], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=HIGH, packets=[NAMED_SOUND_EFFECT[class=PacketPlayOutNamedSoundEffect, id=81]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=HolographicDisplays, sending=ListeningWhitelist[priority=NORMAL, packets=[SPAWN_ENTITY_LIVING[class=PacketPlayOutSpawnEntityLiving, id=2], SPAWN_ENTITY[class=PacketPlayOutSpawnEntity, id=0], ENTITY_METADATA[class=PacketPlayOutEntityMetadata, id=68], REL_ENTITY_MOVE[class=PacketPlayOutRelEntityMove, id=39], REL_ENTITY_MOVE_LOOK[class=PacketPlayOutRelEntityMoveLook, id=40]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=WorldGuardExtraFlags, sending=ListeningWhitelist[priority=NORMAL, packets=[REMOVE_ENTITY_EFFECT[class=PacketPlayOutRemoveEntityEffect, id=55]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=NORMAL, packets=[OUT_SERVER_INFO[class=PacketStatusOutServerInfo, id=0]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=HIGH, packets=[PLAYER_INFO[class=PacketPlayOutPlayerInfo, id=50]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=NORMAL, packets=[PLAYER_INFO[class=PacketPlayOutPlayerInfo, id=50]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=HIGH, packets=[SPAWN_ENTITY_LIVING[class=PacketPlayOutSpawnEntityLiving, id=2], SPAWN_ENTITY[class=PacketPlayOutSpawnEntity, id=0], COLLECT[class=PacketPlayOutCollect, id=85], ENTITY_TELEPORT[class=PacketPlayOutEntityTeleport, id=86], ENTITY_DESTROY[class=PacketPlayOutEntityDestroy, id=54], ENTITY_EFFECT[class=PacketPlayOutEntityEffect, id=89], ENTITY_STATUS[class=PacketPlayOutEntityStatus, id=26], ENTITY_HEAD_ROTATION[class=PacketPlayOutEntityHeadRotation, id=58], REMOVE_ENTITY_EFFECT[class=PacketPlayOutRemoveEntityEffect, id=55], ANIMATION[class=PacketPlayOutAnimation, id=5], ATTACH_ENTITY[class=PacketPlayOutAttachEntity, id=69], ENTITY_VELOCITY[class=PacketPlayOutEntityVelocity, id=70], NAMED_ENTITY_SPAWN[class=PacketPlayOutNamedEntitySpawn, id=4], ENTITY_METADATA[class=PacketPlayOutEntityMetadata, id=68], ENTITY_LOOK[class=PacketPlayOutEntityLook, id=41], ENTITY_EQUIPMENT[class=PacketPlayOutEntityEquipment, id=71], REL_ENTITY_MOVE[class=PacketPlayOutRelEntityMove, id=39], BLOCK_BREAK_ANIMATION[class=PacketPlayOutBlockBreakAnimation, id=8], ENTITY_MOVE_LOOK[class=PacketPlayOutRelEntityMoveLook, id=40]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=HIGH, packets=[WORLD_PARTICLES[class=PacketPlayOutWorldParticles, id=34]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=LOW, packets=[GAME_STATE_CHANGE[class=PacketPlayOutGameStateChange, id=29], PLAYER_INFO[class=PacketPlayOutPlayerInfo, id=50], ABILITIES[class=PacketPlayOutAbilities, id=48], ENTITY_METADATA[class=PacketPlayOutEntityMetadata, id=68]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=PremiumVanish, sending=ListeningWhitelist[priority=NORMAL, packets=[ENTITY_METADATA[class=PacketPlayOutEntityMetadata, id=68], NAMED_ENTITY_SPAWN[class=PacketPlayOutNamedEntitySpawn, id=4]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST]]
packetInjector=com.comphenix.protocol.injector.netty.ProtocolInjector$5@44b896e7
playerInjection=com.comphenix.protocol.injector.netty.ProtocolInjector$4@40a8a40b
inputBufferedPackets=[]
recievedListeners=com.comphenix.protocol.injector.SortedPacketListenerList@14d8aedb
sendingListeners=com.comphenix.protocol.injector.SortedPacketListenerList@cdf6285
hasClosed=false
classLoader=PluginClassLoader{plugin=ProtocolLib v4.6.0, pluginEnabled=true, url=plugins/ProtocolLib.jar}
reporter=com.comphenix.protocol.ProtocolLib$1@c50d257
server=CraftServer{serverName=Purpur,serverVersion=git-Purpur-1171,minecraftVersion=1.16.5}
library=ProtocolLib v4.6.0
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@58226eac
knowsServerPackets=true
knowsClientPackets=true
phaseLoginCount=1
phasePlayingCount=12
packetCreation=true
nettyInjector=com.comphenix.protocol.injector.netty.ProtocolInjector@aca8f56
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@52afffb4
hasRecycleDistance=true
minecraftVersion=(MC: 1.16.5)
debug=false
]
Sender:
com.comphenix.protocol.reflect.compiler.BackgroundCompiler@45236f49[
listeners={com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@81551607=[com.comphenix.protocol.reflect.compiler.BackgroundCompiler$1@32f4799d], com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@cd7e7b9d=[com.comphenix.protocol.injector.StructureCache$1@6c9af0aa], com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@a52dc481=[com.comphenix.protocol.reflect.compiler.BackgroundCompiler$1@41e5e0d2], com.comphenix.protocol.reflect.compiler.StructureCompiler$StructureKey@7963513e=[com.comphenix.protocol.reflect.compiler.BackgroundCompiler$1@1fe28680]}
listenerLock=java.lang.Object@e4b3c70
compiler=com.comphenix.protocol.reflect.compiler.StructureCompiler@356f82b3
enabled=false
shuttingDown=false
executor=java.util.concurrent.Executors$FinalizableDelegatedExecutorService@5b6217bc
reporter=com.comphenix.protocol.ProtocolLib$1@c50d257
unknownPermGenBean=java.lang.Object@503f5cd6
permGenBean=
disablePermGenFraction=0.65
]
Version:
ProtocolLib v4.6.0
Java Version:
16.0.1
Server:
git-Purpur-1171 (MC: 1.16.5)

This is fixed in the 4.7.0 release. Find it here: https://github.com/dmulloy2/ProtocolLib/releases/tag/4.7.0