Prevent array sublists interfering with parent lists

.gitignore

@@ -0,0 +1,3 @@
+target
+.idea
+*.iml

src/main/java/geocode/kdtree/KDTree.java

@@ -26,6 +26,7 @@ of this software and associated documentation files (the "Software"), to deal
 
 package geocode.kdtree;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
@@ -53,7 +54,7 @@ private KDNode<T> createKDTree( List<T> items, int depth ) {
         }
         Collections.sort(items, items.get(0).getComparator(depth % 3));
         int currentIndex = items.size()/2;
-        return new KDNode<T>(createKDTree(items.subList(0, currentIndex), depth+1), createKDTree(items.subList(currentIndex + 1, items.size()), depth+1), items.get(currentIndex));
+        return new KDNode<T>(createKDTree(new ArrayList<T>(items.subList(0, currentIndex)), depth+1), createKDTree(new ArrayList<T>(items.subList(currentIndex + 1, items.size())), depth+1), items.get(currentIndex));
     }
 
     private KDNode<T> findNearest(KDNode<T> currentNode, T search, int depth) {