Registration

Before registering mixins via MixinBooter, you have to consider how your mixins affect the game.

If your mixin affects Vanilla Minecraft or Forge classes, you will need a coremod.

Vanilla Minecraft/Forge Mixins

Make a Coremod
In your IFMLLoadingPlugin implementation, also implement IEarlyMixinLoader

Mod Mixins

Create a class in your mod, anywhere (preferably under your mod's packages).
In your class, implement ILateMixinLoader

Both IEarlyMixinLoader and ILateMixinLoader have identical methods:

java

/**
 * @return mixin configurations to be queued and sent to Mixin library.
 */
List<String> getMixinConfigs();

/**
 * Whether the mixin config should be queued and sent to Mixin library.
 *
 * @param mixinConfig mixin config name, queried via {@link getMixinConfigs()}.
 * @return true if the mixinConfig should be queued, false if it should not.
 */
default boolean shouldMixinConfigQueue(String mixinConfig) {
    return true;
}

/**
 * Runs when a mixin config is successfully queued and sent to Mixin library.
 * @param mixinConfig mixin config name, queried via {@link getMixinConfigs()}.
*/
default void onMixinConfigQueued(String mixinConfig) { }