I am getting errors while creating a custom world with this plugin. I dont think the error is my plugin, because with other worldgenerators it is working well.
Using the 2.6.0 version of your plugin
Error:
[15:58:51] [Server thread/WARN]: java.lang.NoClassDefFoundError: net/minecraft/server/v1_7_R2/WorldProvider
[15:58:51] [Server thread/WARN]: at com.khorn.terraincontrol.bukkit.TCPlugin.getDefaultWorldGenerator(TCPlugin.java:148)
[15:58:51] [Server thread/WARN]: at org.bukkit.WorldCreator.getGeneratorForName(WorldCreator.java:289)
[15:58:51] [Server thread/WARN]: at org.bukkit.WorldCreator.generator(WorldCreator.java:182)
[15:58:51] [Server thread/WARN]: at Bammerbom.UltimateCore.Commands.CmdWorld.create(CmdWorld.java:85)
[15:58:51] [Server thread/WARN]: at Bammerbom.UltimateCore.UltimateCommands.onCmd(UltimateCommands.java:224)
[15:58:51] [Server thread/WARN]: at Bammerbom.UltimateCore.Events.EventCommandHandler.onCommand(EventCommandHandler.java:66)
[15:58:51] [Server thread/WARN]: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[15:58:51] [Server thread/WARN]: at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
[15:58:51] [Server thread/WARN]: at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
[15:58:51] [Server thread/WARN]: at java.lang.reflect.Method.invoke(Unknown Source)
[15:58:51] [Server thread/WARN]: at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:318)
[15:58:51] [Server thread/WARN]: at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
[15:58:51] [Server thread/WARN]: at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:30)
[15:58:51] [Server thread/WARN]: at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:487)
[15:58:51] [Server thread/WARN]: at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:472)
[15:58:51] [Server thread/WARN]: at net.minecraft.server.v1_7_R1.DedicatedServer.aw(DedicatedServer.java:305)
[15:58:51] [Server thread/WARN]: at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:274)
[15:58:51] [Server thread/WARN]: at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:562)
[15:58:51] [Server thread/WARN]: at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:469)
[15:58:51] [Server thread/WARN]: at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617)
[15:58:51] [Server thread/WARN]: Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_7_R2.WorldProvider
[15:58:51] [Server thread/WARN]: at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:67)
[15:58:51] [Server thread/WARN]: at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:62)
[15:58:51] [Server thread/WARN]: at java.lang.ClassLoader.loadClass(Unknown Source)
[15:58:51] [Server thread/WARN]: at java.lang.ClassLoader.loadClass(Unknown Source)
[15:58:51] [Server thread/WARN]: ... 20 more
Command using: "/world create Custom s:12 g:TerrainControl"
Server version: Spigot git-Spigot-1327 (MC 1.7.2) (Implementing API version 1.7.2-R0.4-SNAPSHOT)
It looks like your plugin can't find The WorldProvider class of v1_7_R2. But I am using v1_7_R4. Can you fix this please?
Ps: I developed this "Custom" plugin myself so if you want to see code/etc comment it

You're actually using v1_7_R1. You'll need a 1.7.5 compatible Spigot (or CraftBukkit) build. A 1.7.2 compatible build can be found here.