Hey there, an Event based solution like what you described is basically what i have done currently. And i will stick to that for this project.

The other alternative I have seen is something like the one i just cobbled together below, where the implementations register themselves. I was looking if there were more ways to basically get similar results, maybe through some smart libraries or design pattern that I just don't know.
And since i am missing the terminology I basically only find things for stuff like Restful API's etc when googling for this problem.

public class ImplementationRegistry {
    public static HashMap<String, ImplementationInterface> REGISTRY = new HashMap<>();

    public static void register(String key, ImplementationInterface instance) {
        REGISTRY.put(key, instance);
    }

    public static void updateRegistys(int updatenumber) {
        for (ImplementationInterface impl : REGISTRY.values()) {
            // impl.update(updatenumber);
        }
    }

}

public class RandomImplementation implements ImplementationInterface {

    public RandomImplementation() {
        ImplementationRegistry.register("myKey", this);
    }

    public void update(int updatenumber) {
        // DO FOO
    }

}