Forge 1.20

- Creative mode tabs are now a registry; the `BuildContents` event was renamed to `BuildCreativeModeTabContentsEvent` and moved it to its own class
- The pack format is now 15 for both resource packs and data packs
- `ScreenUtils` was deprecated in favor of a `GuiGraphics` extension
- Forge and the MDK were updated to Gradle 8 and FG6
- The Forge common config file was removed (it only contained the deprecated old fields for resource caching, which was removed in 1.19.3)
- Registry dummy entries were removed
- `RemappingVertexPipeline` was fixed to forward the `endVertex()` call
- Forge tool tags were removed in favor of vanilla ones

Co-authored-by: ChampionAsh5357 <ash@ashwork.net>
Co-authored-by: coehlrich <coehlrich@users.noreply.github.com>
Co-authored-by: Dennis C <11262040+XFactHD@users.noreply.github.com>
Co-authored-by: Matyrobbrt <matyrobbrt@gmail.com>

src/main/java/net/minecraftforge/items/ItemHandlerHelper.java

@@ -38,7 +38,7 @@ public class ItemHandlerHelper
 
     public static boolean canItemStacksStack(@NotNull ItemStack a, @NotNull ItemStack b)
     {
-        if (a.isEmpty() || !a.sameItem(b) || a.hasTag() != b.hasTag())
+        if (a.isEmpty() || !ItemStack.isSameItem(a, b) || a.hasTag() != b.hasTag())
             return false;
 
         return (!a.hasTag() || a.getTag().equals(b.getTag())) && a.areCapsCompatible(b);
@@ -150,7 +150,7 @@ public class ItemHandlerHelper
         if (stack.isEmpty()) return;
 
         IItemHandler inventory = new PlayerMainInvWrapper(player.getInventory());
-        Level level = player.level;
+        Level level = player.level();
 
         // try adding it into the inventory
         ItemStack remainder = stack;