InaccessibleObjectException: [...] module java.base does not "opens java.util" to unnamed module @77e932bf

[Grabsky]

Hello, I'm getting InaccessibleObjectException when using following code. Is that another LuaJ / LuaKT issue?

[13:15:25] [Server thread/ERROR]: Could not pass event PlayerResourcePackStatusEvent to LuaLink v1.20.4-83
org.luaj.vm2.LuaError: @plugins/LuaLink/scripts/welcome.lua:11 vm error: java.lang.reflect.InaccessibleObjectException: Unable to make public java.util.List java.util.Collections$UnmodifiableRandomAccessList.subList(int,int) accessible: module java.base does not "opens java.util" to unnamed module @77e932bf
	at org.luaj.vm2.LuaClosure.execute(LuaClosure.java:506) ~[?:?]
	at org.luaj.vm2.LuaClosure.onInvoke(LuaClosure.java:178) ~[?:?]
	at org.luaj.vm2.LuaClosure.invoke(LuaClosure.java:171) ~[?:?]
	at LuaLink-1.20.4-83.jar/xyz.galaxyy.lualink.lua.LuaScript.registerListener$lambda$0(LuaScript.kt:105) ~[LuaLink-1.20.4-83.jar:?]
	at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:81) ~[paper-api-1.21-R0.1-SNAPSHOT.jar:1.21-62-5a503d7]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[paper-api-1.21-R0.1-SNAPSHOT.jar:?]
	at io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:54) ~[paper-1.21.jar:1.21-62-5a503d7]
	at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.callEvent(PaperPluginManagerImpl.java:131) ~[paper-1.21.jar:1.21-62-5a503d7]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:628) ~[paper-api-1.21-R0.1-SNAPSHOT.jar:?]
	at net.minecraft.server.network.ServerCommonPacketListenerImpl.handleResourcePackResponse(ServerCommonPacketListenerImpl.java:233) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.network.protocol.common.ServerboundResourcePackPacket.handle(ServerboundResourcePackPacket.java:30) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.network.protocol.common.ServerboundResourcePackPacket.handle(ServerboundResourcePackPacket.java:15) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$0(PacketUtils.java:56) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.TickTask.run(TickTask.java:18) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:151) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:24) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1542) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:201) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:125) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1519) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1512) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.util.thread.BlockableEventLoop.managedBlock(BlockableEventLoop.java:135) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.managedBlock(MinecraftServer.java:1471) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:1478) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1323) ~[paper-1.21.jar:1.21-62-5a503d7]
	at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:330) ~[paper-1.21.jar:1.21-62-5a503d7]
	at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make public java.util.List java.util.Collections$UnmodifiableRandomAccessList.subList(int,int) accessible: module java.base does not "opens java.util" to unnamed module @77e932bf
	at java.base/java.lang.reflect.AccessibleObject.throwInaccessibleObjectException(AccessibleObject.java:391) ~[?:?]
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:367) ~[?:?]
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:315) ~[?:?]
	at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:203) ~[?:?]
	at java.base/java.lang.reflect.Method.setAccessible(Method.java:197) ~[?:?]
	at kotlin.reflect.jvm.KCallablesJvm.setAccessible(KCallablesJvm.kt:82) ~[?:?]
	at com.github.only52607.luakt.KotlinFunction.<init>(KotlinFunction.kt:20) ~[?:?]
	at com.github.only52607.luakt.KotlinFunction.<init>(KotlinFunction.kt) ~[?:?]
	at com.github.only52607.luakt.KotlinFunction$Companion.forKFunctions(KotlinFunction.kt:120) ~[?:?]
	at com.github.only52607.luakt.KotlinClass$functions$2.invoke(KotlinClass.kt:75) ~[?:?]
	at com.github.only52607.luakt.KotlinClass$functions$2.invoke(KotlinClass.kt:61) ~[?:?]
	at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74) ~[?:?]
	at com.github.only52607.luakt.KotlinClass.getFunctions(KotlinClass.kt:61) ~[?:?]
	at com.github.only52607.luakt.KotlinClass.getFunction(KotlinClass.kt:101) ~[?:?]
	at com.github.only52607.luakt.KotlinInstance.get(KotlinInstance.kt:43) ~[?:?]
	at com.github.only52607.luakt.KotlinInstance.get(KotlinInstance.kt:59) ~[?:?]
	at org.luaj.vm2.LuaClosure.execute(LuaClosure.java:261) ~[?:?]
	... 26 more

local Bukkit = import "org.bukkit.Bukkit"
local ResourcePackStatus = import "org.bukkit.event.player.PlayerResourcePackStatusEvent$Status"

---

-- Listeing to PlayerResourcePackStatusEvent in order to send welcome/motd message when player joins and loads all server resource-packs.
script.hook("org.bukkit.event.player.PlayerResourcePackStatusEvent", function(event)
    -- Listeing for the SUCCESSFULLY_LOADED status.
    if (event:getStatus() == ResourcePackStatus.SUCCESSFULLY_LOADED) then
        -- Retrieving amount of resource-packs that have been sent to the player.
        local sent = event:getPlayer():getMetadata("sent_resource-packs"):get(0):asInt();
        -- Retrieving amount of resource-packs that have been loaded by the player.
        local loaded =  event:getPlayer():getMetadata("loaded_resource-packs"):get(0):asInt()
        -- Checking whether this resource-pack associated with this event is the last to be loaded by the player.
        if (sent == loaded) then
            Bukkit:dispatchCommand(Bukkit:getConsoleSender(), "dialogs send " .. event:getPlayer():getName() .. " welcome/motd")
        end
    end
end)

As far as I can tell, Player#getMetadata returns unmodifiable list which LuaLink is unable to access.

I'm setting metadata in my plugin that I've written in Java, I'm also able to access it using the same methods.

// Setting metadata so other plugins/scripts can easily tell if player has loaded all resource-packs sent by the server.
final int count = player.getMetadata("sent_resource-packs").get(0).asInt();
player.setMetadata("sent_resource-packs", new FixedMetadataValue(plugin, count + 1));

[Saturn745]

I beleive that Freggy had the same issue while making his own gamemode which he described here. I can't confirm 100% if it is or not but looking up that error suggests to do something similar to what he did.

Can you try adding --add-opens=java.base/java.util=ALL-UNNAMED to the JVM startup arguments?

[Grabsky]

That fixed it, thank you. :)

[Saturn745]

That fixed it, thank you. :)

Yeah. Seems like yet another issue with LuaJ. I am unsure if the same will happen with LuaJava but once I get it working i'll be sure to test the example you gave without those JVM arguments.