Bukkit

We're running Thermos 1.7.10 and get this error:

[17:20:54] [Server thread/INFO]: [LimitedCreative] Enabling LimitedCreative v2.3-SNAPSHOT-8cfc3b7f01
[17:20:54] [Server thread/ERROR]: Error occurred while enabling LimitedCreative v2.3-SNAPSHOT-8cfc3b7f01 (Is it up to date?)
java.lang.NoClassDefFoundError: org/bukkit/event/player/PlayerInteractAtEntityEvent
	at de.jaschastarke.minecraft.limitedcreative.ModCreativeLimits.initialize(ModCreativeLimits.java:33) ~[?:?]
	at de.jaschastarke.modularize.ModuleEntry.initialize(ModuleEntry.java:38) ~[?:?]
	at de.jaschastarke.modularize.ModuleManager.addModule(ModuleManager.java:32) ~[?:?]
	at de.jaschastarke.modularize.ModuleManager.addModule(ModuleManager.java:24) ~[?:?]
	at de.jaschastarke.bukkit.lib.Core.addModule(Core.java:106) ~[?:?]
	at de.jaschastarke.minecraft.limitedcreative.LimitedCreative.onInitialize(LimitedCreative.java:35) ~[?:?]
	at de.jaschastarke.bukkit.lib.Core.onEnable(Core.java:48) ~[?:?]
	at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:316) ~[JavaPlugin.class:1.7.10-1614.58]
	at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:368) [JavaPluginLoader.class:1.7.10-1614.58]
	at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:410) [SimplePluginManager.class:1.7.10-1614.58]
	at org.bukkit.craftbukkit.v1_7_R4.CraftServer.loadPlugin(CraftServer.java:438) [CraftServer.class:1.7.10-1614.58]
	at org.bukkit.craftbukkit.v1_7_R4.CraftServer.enablePlugins(CraftServer.java:372) [CraftServer.class:1.7.10-1614.58]
	at net.minecraft.server.MinecraftServer.func_71243_i(MinecraftServer.java:519) [MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer.func_71222_d(MinecraftServer.java:493) [MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer.func_71247_a(MinecraftServer.java:453) [MinecraftServer.class:?]
	at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:337) [lt.class:?]
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:643) [MinecraftServer.class:?]
	at java.lang.Thread.run(Unknown Source) [?:1.8.0_121]
Caused by: java.lang.ClassNotFoundException: org.bukkit.event.player.PlayerInteractAtEntityEvent
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:440) ~[PluginClassLoader.class:1.7.10-1614.58]
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:211) ~[PluginClassLoader.class:1.7.10-1614.58]
	at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_121]
	at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_121]
	... 18 more