ObsidianBreaker Error

[18:44:26 ERROR]: Could not load 'plugins/ObsidianDestroyer (1).jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: org/bukkit/util/config/Configuration
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:133) ~[spigot-1.7.10.jar:git-Spigot-1571]
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[spigot-1.7.10.jar:git-Spigot-1571]
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [spigot-1.7.10.jar:git-Spigot-1571]
    at org.bukkit.craftbukkit.v1_7_R4.CraftServer.loadPlugins(CraftServer.java:369) [spigot-1.7.10.jar:git-Spigot-1571]
    at net.minecraft.server.v1_7_R4.DedicatedServer.init(DedicatedServer.java:152) [spigot-1.7.10.jar:git-Spigot-1571]
    at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:458) [spigot-1.7.10.jar:git-Spigot-1571]
    at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [spigot-1.7.10.jar:git-Spigot-1571]
Caused by: java.lang.NoClassDefFoundError: org/bukkit/util/config/Configuration
    at com.pandemoneus.obsidianDestroyer.ODConfig.<init>(ODConfig.java:34) ~[?:?]
    at com.pandemoneus.obsidianDestroyer.ObsidianDestroyer.<init>(ObsidianDestroyer.java:26) ~[?:?]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.7.0_65]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) ~[?:1.7.0_65]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.7.0_65]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526) ~[?:1.7.0_65]
    at java.lang.Class.newInstance(Class.java:379) ~[?:1.7.0_65]
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:73) ~[spigot-1.7.10.jar:git-Spigot-1571]
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[spigot-1.7.10.jar:git-Spigot-1571]
    ... 6 more
Caused by: java.lang.ClassNotFoundException: org.bukkit.util.config.Configuration
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:88) ~[spigot-1.7.10.jar:git-Spigot-1571]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:83) ~[spigot-1.7.10.jar:git-Spigot-1571]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425) ~[?:1.7.0_65]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358) ~[?:1.7.0_65]
    at com.pandemoneus.obsidianDestroyer.ODConfig.<init>(ODConfig.java:34) ~[?:?]
    at com.pandemoneus.obsidianDestroyer.ObsidianDestroyer.<init>(ObsidianDestroyer.java:26) ~[?:?]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.7.0_65]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) ~[?:1.7.0_65]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.7.0_65]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526) ~[?:1.7.0_65]
    at java.lang.Class.newInstance(Class.java:379) ~[?:1.7.0_65]
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:73) ~[spigot-1.7.10.jar:git-Spigot-1571]
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[spigot-1.7.10.jar:git-Spigot-1571]
    ... 6 more