Fix item desync when dropping items on 1.17+ servers as 1.13- clients

build-logic/build.gradle.kts

@@ -8,5 +8,5 @@ repositories {
 
 dependencies {
     // version must be manually kept in sync with the one in root project settings.gradle.kts
-    implementation("gradle.plugin.com.github.johnrengelman", "shadow", "7.1.2")
+    implementation("gradle.plugin.com.github.johnrengelman", "shadow", "8.0.0")
 }

bukkit/src/main/java/com/viaversion/viabackwards/BukkitPlugin.java

@@ -19,6 +19,7 @@
 package com.viaversion.viabackwards;
 
 import com.viaversion.viabackwards.api.ViaBackwardsPlatform;
+import com.viaversion.viabackwards.listener.PlayerItemDropListener;
 import com.viaversion.viabackwards.listener.FireDamageListener;
 import com.viaversion.viabackwards.listener.FireExtinguishListener;
 import com.viaversion.viabackwards.listener.LecternInteractListener;
@@ -58,6 +59,9 @@ public class BukkitPlugin extends JavaPlugin implements ViaBackwardsPlatform {
     private void onServerLoaded() {
         BukkitViaLoader loader = (BukkitViaLoader) Via.getManager().getLoader();
         int protocolVersion = Via.getAPI().getServerVersion().highestSupportedVersion();
+        if (protocolVersion >= ProtocolVersion.v1_17.getVersion()) {
+            loader.storeListener(new PlayerItemDropListener(this)).register();
+        }
         if (protocolVersion >= ProtocolVersion.v1_16.getVersion()) {
             loader.storeListener(new FireExtinguishListener(this)).register();
         }

bukkit/src/main/java/com/viaversion/viabackwards/listener/PlayerItemDropListener.java

@@ -0,0 +1,48 @@
+
+/*
+ * This file is part of ViaBackwards - https://github.com/ViaVersion/ViaBackwards
+ * Copyright (C) 2016-2023 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viabackwards.listener;
+
+import com.viaversion.viabackwards.BukkitPlugin;
+import com.viaversion.viabackwards.protocol.protocol1_13to1_13_1.Protocol1_13To1_13_1;
+import com.viaversion.viaversion.bukkit.listeners.ViaBukkitListener;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.player.PlayerDropItemEvent;
+import org.bukkit.inventory.ItemStack;
+
+public class PlayerItemDropListener extends ViaBukkitListener {
+
+    public PlayerItemDropListener(final BukkitPlugin plugin) {
+        super(plugin, Protocol1_13To1_13_1.class); // Starts with 1.13 clients on 1.17 servers
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
+    public void onItemDrop(final PlayerDropItemEvent event) {
+        final Player player = event.getPlayer();
+        if (!isOnPipe(player)) {
+            return;
+        }
+
+        // Resent the item in the hand
+        final int slot = player.getInventory().getHeldItemSlot();
+        final ItemStack item = player.getInventory().getItem(slot);
+        player.getInventory().setItem(slot, item);
+    }
+}

settings.gradle.kts

@@ -16,7 +16,7 @@ dependencyResolutionManagement {
 pluginManagement {
     plugins {
         id("net.kyori.blossom") version "1.2.0"
-        id("com.github.johnrengelman.shadow") version "7.1.2"
+        id("com.github.johnrengelman.shadow") version "8.0.0"
     }
 }