[SEVERE] Could not pass event PLAYER_JOIN to BukkitContrib
java.lang.NoSuchFieldError: a
	at org.bukkitcontrib.player.ContribCraftPlayer.<init>(ContribCraftPlayer.java:41)
	at org.bukkitcontrib.player.ContribCraftPlayer.updateBukkitEntity(ContribCraftPlayer.java:197)
	at org.bukkitcontrib.ContribPlayerListener.onPlayerJoin(ContribPlayerListener.java:21)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:244)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:58)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:321)
	at net.minecraft.server.ServerConfigurationManager.c(ServerConfigurationManager.java:124)
	at net.minecraft.server.NetLoginHandler.b(NetLoginHandler.java:97)
	at net.minecraft.server.NetLoginHandler.a(NetLoginHandler.java:33)
	at net.minecraft.server.NetworkListenThread.a(SourceFile:91)
	at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:451)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:361)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)