Only allow non-zero value maxDistances for BlockIterators

Prevents them from iterating infinitely and hanging the server

Spigot-API-Patches/0036-Only-allow-non-zero-maxDistance-BlockIterators.patch

@@ -0,0 +1,23 @@
+From 74c1e1dfd8eaaa86e68838b823ebd5177f007066 Mon Sep 17 00:00:00 2001
+From: Zach Brown <zach.brown@destroystokyo.com>
+Date: Tue, 12 Apr 2016 23:06:56 -0500
+Subject: [PATCH] Only allow non-zero maxDistance BlockIterators
+
+They can iterate infinitely causing the server to hang.
+Fix your plugins!
+
+diff --git a/src/main/java/org/bukkit/util/BlockIterator.java b/src/main/java/org/bukkit/util/BlockIterator.java
+index 5c85778..0f34c66 100644
+--- a/src/main/java/org/bukkit/util/BlockIterator.java
++++ b/src/main/java/org/bukkit/util/BlockIterator.java
+@@ -52,6 +52,7 @@ public class BlockIterator implements Iterator<Block> {
+      *
+      */
+     public BlockIterator(World world, Vector start, Vector direction, double yOffset, int maxDistance) {
++        com.google.common.base.Preconditions.checkArgument(maxDistance != 0, "maxDistance cannot be 0!"); // Paper - Only allow non-zero maxDistance
+         this.world = world;
+         this.maxDistance = maxDistance;
+ 
+-- 
+2.8.0
+