/gt tree.OAK causes an exception

[obsd-guru]

[16:05:23 INFO]:bla issued server command: /gt tree.OAK [16:05:26 WARN]: [GiantTrees] Task #12 for GiantTrees v1.1 generated an exception java.lang.VerifyError: class com.ryanmichela.trees.history.NoChangeBukkitWorld overrides final method setBlockType.(Lcom/sk89q/worldedit/Vector;I)Z at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.8.0_121] at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[?:1.8.0_121] at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:1.8.0_121] at java.net.URLClassLoader.defineClass(URLClassLoader.java:467) ~[?:1.8.0_121] at java.net.URLClassLoader.access$100(URLClassLoader.java:73) ~[?:1.8.0_121] at java.net.URLClassLoader$1.run(URLClassLoader.java:368) ~[?:1.8.0_121] at java.net.URLClassLoader$1.run(URLClassLoader.java:362) ~[?:1.8.0_121] at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_121] at java.net.URLClassLoader.findClass(URLClassLoader.java:361) ~[?:1.8.0_121] at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:77) ~[craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at org.bukkit.plugin.java.JavaPluginLoader.getClassByName(JavaPluginLoader.java:189) ~[craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:73) ~[craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:62) ~[craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_121] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_121] at com.ryanmichela.trees.rendering.WorldChangeTracker.applyChanges(WorldChangeTracker.java:72) ~[?:?] at com.ryanmichela.trees.rendering.Draw3d.applyChanges(Draw3d.java:41) ~[?:?] at com.ryanmichela.trees.rendering.TreeRenderer$1$1.run(TreeRenderer.java:85) ~[?:?] at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftTask.run(CraftTask.java:53) ~[craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:352) [craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at net.minecraft.server.v1_11_R1.MinecraftServer.D(MinecraftServer.java:689) [craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at net.minecraft.server.v1_11_R1.DedicatedServer.D(DedicatedServer.java:360) [craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at net.minecraft.server.v1_11_R1.MinecraftServer.C(MinecraftServer.java:650) [craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at net.minecraft.server.v1_11_R1.MinecraftServer.run(MinecraftServer.java:554) [craftbukkit-1.11.2.jar:git-Bukkit-a1d3777] at java.lang.Thread.run(Thread.java:745) [?:1.8.0_121]