code: public static void registerKey(Binder binder, Key<DruidNode> key)
    {
      DruidBinders.discoveryAnnouncementBinder(binder).addBinding().toInstance(new KeyHolder<>(key));
      LifecycleModule.register(binder, ServiceAnnouncer.class);
    }
docs: Requests that the keyed DruidNode instance be injected and published as part of the lifecycle.
  
  That is, this module will announce the DruidNode instance returned by
  injector.getInstance(Key.get(DruidNode.class, annotation)) automatically.
  Announcement will happen in the ANNOUNCEMENTS stage of the Lifecycle
  
  @param binder the Binder to register with
  @param key The key to use in finding the DruidNode instance