Error

java.lang.IllegalArgumentException: Plugin already initialized!
        at org.bukkit.plugin.java.PluginClassLoader.initialize(PluginClassLoader
.java:122) ~[spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.plugin.java.JavaPlugin.<init>(JavaPlugin.java:67) ~[spigot
.jar:git-Spigot-9797151-301db84]
        at future.blue.fun.main.<init>(main.java:15) ~[?:?]
        at future.blue.fun.commands.SetGlow.<init>(SetGlow.java:20) ~[?:?]
        at future.blue.fun.main.registerCommands(main.java:31) ~[?:?]
        at future.blue.fun.main.onEnable(main.java:20) ~[?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:292) ~[s
pigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader
.java:340) [spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManage
r.java:405) [spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.craftbukkit.v1_10_R1.CraftServer.loadPlugin(CraftServer.ja
va:362) [spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.craftbukkit.v1_10_R1.CraftServer.enablePlugins(CraftServer
.java:322) [spigot.jar:git-Spigot-9797151-301db84]
        at net.minecraft.server.v1_10_R1.MinecraftServer.t(MinecraftServer.java:
417) [spigot.jar:git-Spigot-9797151-301db84]
        at net.minecraft.server.v1_10_R1.MinecraftServer.l(MinecraftServer.java:
382) [spigot.jar:git-Spigot-9797151-301db84]
        at net.minecraft.server.v1_10_R1.MinecraftServer.a(MinecraftServer.java:
337) [spigot.jar:git-Spigot-9797151-301db84]
        at net.minecraft.server.v1_10_R1.DedicatedServer.init(DedicatedServer.ja
va:270) [spigot.jar:git-Spigot-9797151-301db84]
        at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.jav
a:540) [spigot.jar:git-Spigot-9797151-301db84]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_101]
Caused by: java.lang.IllegalStateException: Initial initialization
        at org.bukkit.plugin.java.PluginClassLoader.initialize(PluginClassLoader
.java:125) ~[spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.plugin.java.JavaPlugin.<init>(JavaPlugin.java:67) ~[spigot
.jar:git-Spigot-9797151-301db84]
        at future.blue.fun.main.<init>(main.java:15) ~[?:?]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 ~[?:1.8.0_101]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
 ~[?:1.8.0_101]
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Sou
rce) ~[?:1.8.0_101]
        at java.lang.reflect.Constructor.newInstance(Unknown Source) ~[?:1.8.0_1
01]
        at java.lang.Class.newInstance(Unknown Source) ~[?:1.8.0_101]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.jav
a:76) ~[spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.j
ava:131) ~[spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.
java:329) ~[spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager
.java:251) ~[spigot.jar:git-Spigot-9797151-301db84]
        at org.bukkit.craftbukkit.v1_10_R1.CraftServer.loadPlugins(CraftServer.j
ava:297) ~[spigot.jar:git-Spigot-9797151-301db84]
        at net.minecraft.server.v1_10_R1.DedicatedServer.init(DedicatedServer.ja
va:202) ~[spigot.jar:git-Spigot-9797151-301db84]
        ... 2 more