PaperMC/patches/server/1046-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 fe6e1e23b94d35ab5a2ba9c70bbc41820636c7df..c54df6e4aed9b7b46a41af4108a8e90d96c1fe1f 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -2347,8 +2347,10 @@ 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)));
         }
     }