[23:59:38] [Server thread/INFO]: [LookHologram] Enabling LookHologram v1.0
[23:59:38] [Server thread/ERROR]: Error occurred while enabling LookHologram v1.0 (Is it up to date?)
java.lang.NoClassDefFoundError: net/minecraft/server/v1_15_R1/World
    at me.neznamy.lookhologram.Main.load(Main.java:90) ~[?:?]
    at me.neznamy.lookhologram.Main.onEnable(Main.java:48) ~[?:?]
    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:263) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:351) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:480) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at org.bukkit.craftbukkit.v1_16_R1.CraftServer.enablePlugin(CraftServer.java:491) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at org.bukkit.craftbukkit.v1_16_R1.CraftServer.enablePlugins(CraftServer.java:405) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at net.minecraft.server.v1_16_R1.MinecraftServer.loadWorld(MinecraftServer.java:438) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at net.minecraft.server.v1_16_R1.DedicatedServer.init(DedicatedServer.java:219) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at net.minecraft.server.v1_16_R1.MinecraftServer.v(MinecraftServer.java:810) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at net.minecraft.server.v1_16_R1.MinecraftServer.lambda$0(MinecraftServer.java:164) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_211]
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_15_R1.World
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:96) ~[spigot.jar:git-Spigot-ad703da-e2403a3]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_211]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_211]
    ... 12 more