IgnoreElementsObservable.java

        Observable.range(1, 10)
                .ignoreElements()
                .subscribe(new CompletableObserver() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        System.out.println("onSubscribed");
                    }

                    @Override
                    public void onComplete() {
                        System.out.println("Completed");
                    }

                    @Override
                    public void onError(Throwable e) {

                    }
                });