From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MrPowerGamerBR <git@mrpowergamerbr.com>
Date: Fri, 21 Jun 2024 18:07:25 -0300
Subject: [PATCH] Allow item version downgrades

The server WON'T convert the item data from a newer version to an older version, so proceed with caution

diff --git a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
index bd8005cd3a52532f4cb2e123da473f1490b59dbb..2d23110b61024847c8ed554ac5652982a35dd74b 100644
--- a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+++ b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
@@ -85,6 +85,7 @@ import org.bukkit.potion.PotionType;
 public final class CraftMagicNumbers implements UnsafeValues {
     public static final CraftMagicNumbers INSTANCE = new CraftMagicNumbers();
     public static final boolean DISABLE_OLD_API_SUPPORT = Boolean.getBoolean("paper.disableOldApiSupport"); // Paper
+    private static final boolean JUST_CORRUPT_IT = Boolean.getBoolean("sparklypaper.ignoreItemDataVersion"); // SparklyPaper - allow item downgrades
 
     private final Commodore commodore = new Commodore();
 
@@ -246,7 +247,7 @@ public final class CraftMagicNumbers implements UnsafeValues {
     @Override
     public Material getMaterial(String material, int version) {
         Preconditions.checkArgument(material != null, "material == null");
-        Preconditions.checkArgument(version <= this.getDataVersion(), "Newer version! Server downgrades are not supported!");
+        Preconditions.checkArgument(JUST_CORRUPT_IT || version <= this.getDataVersion(), "Newer version! Server downgrades are not supported!"); // SparklyPaper - allow item downgrades
 
         // Fastpath up to date materials
         if (version == this.getDataVersion()) {
@@ -676,7 +677,7 @@ public final class CraftMagicNumbers implements UnsafeValues {
             throw new RuntimeException(ex);
         }
         int dataVersion = compound.getInt("DataVersion");
-        Preconditions.checkArgument(dataVersion <= getDataVersion(), "Newer version! Server downgrades are not supported!");
+        Preconditions.checkArgument(JUST_CORRUPT_IT || dataVersion <= getDataVersion(), "Newer version! Server downgrades are not supported!"); // SparklyPaper - allow item downgrades
         return compound;
     }