Convert compact sound list to single entry in registry data

Author: kennytv

common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_11to1_21_9/Protocol1_21_11To1_21_9.java

@@ -34,6 +34,7 @@
 import com.viaversion.viabackwards.protocol.v1_21_11to1_21_9.rewriter.EntityPacketRewriter1_21_11;
 import com.viaversion.viabackwards.protocol.v1_21_11to1_21_9.storage.GameTimeStorage;
 import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.data.FullMappings;
 import com.viaversion.viaversion.api.minecraft.entities.EntityTypes1_21_11;
 import com.viaversion.viaversion.api.protocol.packet.provider.PacketTypesProvider;
 import com.viaversion.viaversion.api.protocol.packet.provider.SimplePacketTypesProvider;
@@ -73,7 +74,23 @@ public final class Protocol1_21_11To1_21_9 extends BackwardsProtocol<Clientbound
     private final ParticleRewriter<ClientboundPacket1_21_11> particleRewriter = new ParticleRewriter<>(this);
     private final NBTComponentRewriter<ClientboundPacket1_21_11> translatableRewriter = new ComponentRewriter1_21_11(this);
     private final TagRewriter<ClientboundPacket1_21_11> tagRewriter = new TagRewriter<>(this);
-    private final RegistryDataRewriter registryDataRewriter = new BackwardsRegistryRewriter(this);
+    private final RegistryDataRewriter registryDataRewriter = new BackwardsRegistryRewriter(this) {
+        @Override
+        protected void updateType(final CompoundTag tag, final String key, final FullMappings mappings) {
+            super.updateType(tag, key, mappings);
+
+            if (key.equals("sound") && tag.get(key) instanceof ListTag<?> listTag) {
+                // From a compact list to a single value
+                final Tag first;
+                if (listTag.isEmpty()) {
+                    first = new StringTag(mappings.mappedIdentifier(0)); // Dummy
+                } else {
+                    first = listTag.get(0);
+                }
+                tag.put(key, first);
+            }
+        }
+    };
 
     public Protocol1_21_11To1_21_9() {
         super(ClientboundPacket1_21_11.class, ClientboundPacket1_21_9.class, ServerboundPacket1_21_9.class, ServerboundPacket1_21_9.class);