[Bleeding] Add iterator() with starting index. Addresses BUKKIT-1246

src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java

@@ -381,6 +381,13 @@ public class CraftInventory implements Inventory {
         return new InventoryIterator(this);
     }
 
+    public ListIterator<ItemStack> iterator(int index) {
+        if (index < 0) {
+            index += getSize() + 1; // ie, with -1, previous() will return the last element
+        }
+        return new InventoryIterator(this, index);
+    }
+
     public List<HumanEntity> getViewers() {
         return this.inventory.getViewers();
     }

src/main/java/org/bukkit/craftbukkit/inventory/InventoryIterator.java

@@ -8,13 +8,18 @@ import org.bukkit.inventory.ItemStack;
 public class InventoryIterator implements ListIterator<ItemStack> {
     private final Inventory inventory;
     private int nextIndex;
-    private boolean lastDirection; // true = forward, false = backward
+    private Boolean lastDirection; // true = forward, false = backward, null = haven't moved yet
 
     InventoryIterator(Inventory craftInventory) {
         this.inventory = craftInventory;
         this.nextIndex = 0;
     }
 
+    InventoryIterator(Inventory craftInventory, int index) {
+        this.inventory = craftInventory;
+        this.nextIndex = index;
+    }
+
     public boolean hasNext() {
         return nextIndex < inventory.getSize();
     }
@@ -42,6 +47,9 @@ public class InventoryIterator implements ListIterator<ItemStack> {
     }
 
     public void set(ItemStack item) {
+        if (lastDirection == null) {
+            throw new IllegalStateException("No current item!");
+        }
         int i = lastDirection ? nextIndex - 1 : nextIndex;
         inventory.setItem(i, item);
     }