PaperMC/patches/server/0018-Keep-previous-behavior-for-setResourcePack.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Fri, 8 Dec 2023 15:06:16 -0800
Subject: [PATCH] Keep previous behavior for setResourcePack

Before multiple packs were allowed, setResourcePack
resulted in the client's existing server pack being
replaced. To keep this behavior, we will remove all
packs before sending the new pack. Other API exists
for adding a new pack to the existing packs on a client.

diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index 87e7071a381540be3b1db55f5d606e9e1e117b39..afdc702682af7ddf338fe00a1b1912766e728f41 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -1803,8 +1803,10 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         if (hash != null) {
             Preconditions.checkArgument(hash.length == 20, "Resource pack hash should be 20 bytes long but was %s", hash.length);
 
+            this.getHandle().connection.send(new net.minecraft.network.protocol.common.ClientboundResourcePackPopPacket(Optional.empty())); // Paper - keep previous behavior of clearing packs
             this.getHandle().connection.send(new ClientboundResourcePackPushPacket(id, url, BaseEncoding.base16().lowerCase().encode(hash), force, CraftChatMessage.fromStringOrNull(prompt, true)));
         } else {
+            this.getHandle().connection.send(new net.minecraft.network.protocol.common.ClientboundResourcePackPopPacket(Optional.empty())); // Paper - keep previous behavior of clearing packs
             this.getHandle().connection.send(new ClientboundResourcePackPushPacket(id, url, "", force, CraftChatMessage.fromStringOrNull(prompt, true)));
         }
     }