Improve equal item listing.

Change when items should be grouped.
Instead of relaying strictly from ignoreMetaData set, now try to group equal elements without durability check, and use set only if that fails.

src/main/java/world/bentobox/challenges/utils/Utils.java

@@ -7,16 +7,12 @@
 import java.util.Locale;
 import java.util.Set;
 
-import org.bukkit.ChatColor;
-import org.bukkit.Material;
-import org.bukkit.Statistic;
-import org.bukkit.World;
+import org.bukkit.*;
 import org.bukkit.enchantments.Enchantment;
 import org.bukkit.entity.EntityType;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.*;
 import org.bukkit.potion.PotionData;
-import org.bukkit.potion.PotionEffectType;
 import org.bukkit.potion.PotionType;
 import org.eclipse.jdt.annotation.Nullable;
 
@@ -31,6 +27,31 @@
  */
 public class Utils
 {
+	/**
+	 * This method checks if 2 given item stacks are similar without durability check.
+	 * @param input First item.
+	 * @param stack Second item.
+	 * @return {@code true} if items are equal, {@code false} otherwise.
+	 */
+	public static boolean isSimilarNoDurability(@Nullable ItemStack input, @Nullable ItemStack stack)
+	{
+		if (stack == null || input == null)
+		{
+			return false;
+		}
+		else if (stack == input)
+		{
+			return true;
+		}
+		else
+		{
+			return input.getType() == stack.getType() &&
+				input.hasItemMeta() == stack.hasItemMeta() &&
+				(!input.hasItemMeta() || Bukkit.getItemFactory().equals(input.getItemMeta(), stack.getItemMeta()));
+		}
+	}
+
+
 	/**
 	 * This method groups input items in single itemstack with correct amount and returns it.
 	 * Allows to remove duplicate items from list.
@@ -55,7 +76,8 @@ public static List<ItemStack> groupEqualItems(List<ItemStack> requiredItems, Set
 				ItemStack required = returnItems.get(i);
 
 				// Merge items which meta can be ignored or is similar to item in required list.
-				if (ignoreMetaData.contains(item.getType()) && item.getType().equals(required.getType()))
+				if (Utils.isSimilarNoDurability(required, item) ||
+					ignoreMetaData.contains(item.getType()) && item.getType().equals(required.getType()))
 				{
 					required.setAmount(required.getAmount() + item.getAmount());
 					isUnique = false;