Mitigate spigot issue when setting wolf owner

This fixes the Summon Wolves spell in Wizards.

Explanation:

- Wolves keep track of their most recent owner.
- When a wolf is assigned a new owner, it updates the data
  watcher with the new owner's UUID
- During this process, the old owner's UUID is checked
  against the new one
- If the wolf didn't have a previous owner, the old owner's
  UUID is the empty string.
- UUID.fromString() is called on the empty string, and throws
  an exception.

Plugins/Nautilus.Game.Arcade/src/nautilus/game/arcade/game/games/wizards/spells/SpellSummonWolves.java

@@ -4,6 +4,7 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Random;
 
+import com.google.common.base.Optional;
 import mineplex.core.common.util.UtilBlock;
 import mineplex.core.common.util.UtilParticle;
 import mineplex.core.common.util.UtilServer;
@@ -16,17 +17,15 @@ import nautilus.game.arcade.game.games.wizards.Spell;
 import nautilus.game.arcade.game.games.wizards.spellinterfaces.SpellClick;
 import nautilus.game.arcade.game.games.wizards.spellinterfaces.SpellClickBlock;
 
+import net.minecraft.server.v1_8_R3.EntityWolf;
 import org.bukkit.DyeColor;
 import org.bukkit.Effect;
 import org.bukkit.Location;
 import org.bukkit.Sound;
 import org.bukkit.block.Block;
 import org.bukkit.block.BlockFace;
-import org.bukkit.entity.AnimalTamer;
+import org.bukkit.craftbukkit.v1_8_R3.entity.CraftWolf;
-import org.bukkit.entity.Entity;
+import org.bukkit.entity.*;
-import org.bukkit.entity.EntityType;
-import org.bukkit.entity.Player;
-import org.bukkit.entity.Wolf;
 import org.bukkit.event.EventHandler;
 
 public class SpellSummonWolves extends Spell implements SpellClick, SpellClickBlock
@@ -57,6 +56,7 @@ public class SpellSummonWolves extends Spell implements SpellClick, SpellClickBl
 
 			wolf.setCollarColor(DyeColor.YELLOW);
 			wolf.setTamed(true);
+			setOldOwner_ReplaceMeWhenSpigotFixesThis(wolf, player);
 			wolf.setOwner(player);
 			wolf.setBreed(false);
 			wolf.setCustomName(player.getDisplayName() + "'s Wolf");
@@ -73,6 +73,24 @@ public class SpellSummonWolves extends Spell implements SpellClick, SpellClickBl
 		charge(player);
 	}
 
+	// Explanation:
+	// - Wolves keep track of their most recent owner.
+	// - When a wolf is assigned a new owner, it updates the data watcher
+	//   with the new owner's UUID
+	// - During this process, the old owner's UUID is checked against
+	//   the new one
+	// - If the wolf didn't have a previous owner, the old owner's UUID
+	//   is the empty string.
+	// - UUID.fromString() is called on the empty string, and throws
+	//   an exception.
+	//
+	// We mitigate the issue by manually setting the old owner's UUID
+	// to that of the player.
+	private void setOldOwner_ReplaceMeWhenSpigotFixesThis(Wolf wolf, Player player)
+	{
+		((CraftWolf)wolf).getHandle().getDataWatcher().watch(17, player.getUniqueId().toString(), EntityWolf.META_OWNER, Optional.absent());
+	}
+
 	@EventHandler
 	public void onDamage(CustomDamageEvent event)
 	{