FAF — Fiojf's Attribute Swap Fix

A Paper 1.21.11 plugin that restores vanilla attribute swapping behavior on servers.

What is Attribute Swapping?

Attribute swapping (MC-28289) is a vanilla Minecraft mechanic where swapping weapons within 1-2 ticks of an attack causes the game to mix attributes from both items — using one weapon's base damage with another weapon's enchantments.

Paper prevents this by forcing equipment updates on player actions. FAF undoes that fix, restoring vanilla behavior.

How it Works

1. Disables Paper's update-equipment-on-player-actions at runtime via reflection
2. Preserves the attack cooldown ticker across item swaps using NMS reflection, counteracting Paper's cooldown reset
3. Falls back to temporary attribute modifiers if the config toggle is unavailable

Installation

1. Drop faf-1.0.0.jar into your server's plugins/ folder
2. Restart the server
3. Attribute swapping is enabled by default

Commands

Command	Permission	Description
/faf	faf.toggle	Toggle vanilla attribute swap on/off

Permission defaults to op.

Config

# config.yml
enabled: true

Building

Requires Java 21 and Maven.

mvn clean package

The jar will be in target/faf-1.0.0.jar.

License

LGPL-3.0-only