Have BukkitEntity.getState() return null for now.

src/bukkit/java/com/sk89q/worldedit/bukkit/BukkitEntity.java

@@ -74,7 +74,7 @@ class BukkitEntity implements Entity {
 
     @Override
     public BaseEntity getState() {
-        throw new UnsupportedOperationException("Not implemented yet");
+        return null;
     }
 
     @Override

src/main/java/com/sk89q/worldedit/entity/Entity.java

@@ -22,6 +22,8 @@ package com.sk89q.worldedit.entity;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.util.Location;
 
+import javax.annotation.Nullable;
+
 /**
  * A reference to an instance of an entity that exists in an {@link Extent}
  * and thus would have position and similar details.
@@ -37,8 +39,9 @@ public interface Entity {
     /**
      * Get a copy of the entity's state.
      *
-     * @return the entity's state
+     * @return the entity's state or null if one cannot be gotten
      */
+    @Nullable
     BaseEntity getState();
 
     /**