When RiftLoader#newInstance is invoked, it does not check for a pre-existing class instance in RiftLoader#listenerInstanceMap. This means that RiftLoader#setInstanceForListenerClass is effectively non-functional. When looking to create an instance of the given class, it should run a map lookup to check for a pre-existing instance before trying to reflect the constructors or delegate to Instantiator's.

A test case that will produce an issue with the current code can be seen below. An instance is assigned for the class on static initialization, ensuring there is a supplied instance long before RiftLoader tries to create one - but since the instance map is never checked against, this will still crash with an InstantiationException.

public final class MyListenerClass implements InitializationListener {
    public static final MyListenerClass INSTANCE = new MyListenerClass();
    
    static {
        RiftLoader.instance.setInstanceForListenerClass(MyListenerClass.class, MyListenerClass.INSTANCE);
    }
    
    private MyListenerClass() {}
    
    @Override
    public void onInitialization() {}
}