code: @SuppressWarnings("unchecked")
  	public static <T> CorePublisher<T> onLastAssembly(CorePublisher<T> source) {
  		Function<Publisher, Publisher> hook = Hooks.onLastOperatorHook;
  		final Publisher<T> publisher;
  		if (hook == null) {
  			publisher = source;
  		}
  		else {
  			publisher = Objects.requireNonNull(hook.apply(source),"LastOperator hook returned null");
  		}
  
  		if (publisher instanceof CorePublisher) {
  			return (CorePublisher<T>) publisher;
  		}
  		else {
  			return new CorePublisherAdapter<>(publisher);
  		}
  	}
docs: Applies the hooks registered with {@link Hooks#onLastOperator} and returns
  {@link CorePublisher} ready to be subscribed on.
  
  @param source the original {@link CorePublisher}.
  @param <T> the type of the value.
  @return a {@link CorePublisher} to subscribe on.