SPIGOT-4122: Fix an instance of legacy item inequalities

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/inventory/ItemStack.java

@@ -254,7 +254,8 @@ public class ItemStack implements Cloneable, ConfigurationSerializable {
         if (stack == this) {
             return true;
         }
-        return getType()== stack.getType()&& getDurability() == stack.getDurability() && hasItemMeta() == stack.hasItemMeta() && (hasItemMeta() ? Bukkit.getItemFactory().equals(getItemMeta(), stack.getItemMeta()) : true);
+        Material comparisonType = Bukkit.getUnsafe().fromLegacy(this.getType()); // This may be called from legacy item stacks, try to get the right material
+        return comparisonType == stack.getType() && getDurability() == stack.getDurability() && hasItemMeta() == stack.hasItemMeta() && (hasItemMeta() ? Bukkit.getItemFactory().equals(getItemMeta(), stack.getItemMeta()) : true);
     }
 
     @Override