add mutable bv3 to queue instead i guess

Author: eztaK-red

worldedit-core/src/main/java/com/sk89q/worldedit/EditSession.java

@@ -3644,10 +3644,12 @@ public Set<BlockVector3> getHollowed(Set<BlockVector3> vset) {
     }
 
     private void recurseHollow(Region region, BlockVector3 origin, Set<BlockVector3> outside, Mask mask) {
-        // FAWE start - use BlockVector3Set instead of LinkedList
+        // FAWE start - use BlockVector3Set instead of LinkedList & mutable BV3
         final BlockVector3Set queue = BlockVector3Set.getAppropriateVectorSet(region);
         queue.add(origin);
 
+        MutableBlockVector3 mutable = new MutableBlockVector3();
+
         while (!queue.isEmpty()) {
             Iterator<BlockVector3> iter = queue.iterator();
             while (iter.hasNext()) {
@@ -3664,7 +3666,7 @@ private void recurseHollow(Region region, BlockVector3 origin, Set<BlockVector3>
                 }
 
                 for (BlockVector3 recurseDirection : recurseDirections) {
-                    queue.add(current.toImmutable().add(recurseDirection));
+                    queue.add(mutable.setComponents(current).add(recurseDirection));
                 }
             }
         }