rror occurred while enabling ItemsAdder v3.6.2d-beta-2 (Is it up to date?)

Console
19:18:21

java.lang.NoClassDefFoundError: Could not initialize class ia.m.my
at dev.lone.itemsadder.Main.onEnable(SourceFile:221) ~[ItemsAdder.jar:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:281) ~[slimeworldmanager-api-1.20.2-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.manager.PaperPluginInstanceManager.enablePlugin(PaperPluginInstanceManager.java:190) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.enablePlugin(PaperPluginManagerImpl.java:104) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:507) ~[slimeworldmanager-api-1.20.2-R0.1-SNAPSHOT.jar:?]
at org.bukkit.craftbukkit.v1_20_R2.CraftServer.enablePlugin(CraftServer.java:646) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at org.bukkit.craftbukkit.v1_20_R2.CraftServer.enablePlugins(CraftServer.java:557) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at net.minecraft.server.MinecraftServer.loadWorld0(MinecraftServer.java:642) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at net.minecraft.server.MinecraftServer.loadLevel(MinecraftServer.java:424) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:308) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1101) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:315) ~[slimeworldmanager-1.20.2.jar:git-SlimeWorldManager-15575]
at java.lang.Thread.run(Thread.java:833) ~[?:?]