[16:10:30 ERROR]: Error occurred while enabling OwnEssentials v1.0.0 (Is it up to date?)
java.lang.IllegalArgumentException: Plugin already initialized!
        at org.bukkit.plugin.java.PluginClassLoader.initialize(PluginClassLoader.java:122) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.plugin.java.JavaPlugin.<init>(JavaPlugin.java:67) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at de.vollexstudios.Listener.JoinListener.<init>(JoinListener.java:16) ~[?:?]
        at de.vollexstudios.MainClass.initListener(MainClass.java:54) ~[?:?]
        at de.vollexstudios.MainClass.onEnable(MainClass.java:22) ~[?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:292) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:340) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.craftbukkit.v1_9_R1.CraftServer.loadPlugin(CraftServer.java:361) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.craftbukkit.v1_9_R1.CraftServer.enablePlugins(CraftServer.java:321) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.craftbukkit.v1_9_R1.CraftServer.reload(CraftServer.java:745) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.Bukkit.reload(Bukkit.java:539) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.craftbukkit.v1_9_R1.CraftServer.dispatchCommand(CraftServer.java:645) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.craftbukkit.v1_9_R1.CraftServer.dispatchServerCommand(CraftServer.java:631) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at net.minecraft.server.v1_9_R1.DedicatedServer.aL(DedicatedServer.java:438) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at net.minecraft.server.v1_9_R1.DedicatedServer.D(DedicatedServer.java:401) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at net.minecraft.server.v1_9_R1.MinecraftServer.C(MinecraftServer.java:660) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:559) [spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_91]
Caused by: java.lang.IllegalStateException: Initial initialization
        at org.bukkit.plugin.java.PluginClassLoader.initialize(PluginClassLoader.java:125) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.plugin.java.JavaPlugin.<init>(JavaPlugin.java:67) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at de.vollexstudios.MainClass.<init>(MainClass.java:12) ~[?:?]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_91]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_91]
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_91]
        at java.lang.reflect.Constructor.newInstance(Unknown Source) ~[?:1.8.0_91]
        at java.lang.Class.newInstance(Unknown Source) ~[?:1.8.0_91]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:76) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.craftbukkit.v1_9_R1.CraftServer.loadPlugins(CraftServer.java:296) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        at org.bukkit.craftbukkit.v1_9_R1.CraftServer.reload(CraftServer.java:743) ~[spigot.jar:git-Spigot-2038f4a-cd36f6f]
        ... 10 more