Cannot receive callback from Flowable when exec DELETE on Room

[fengshenzhu]

In BasicRxJavaSampleKotlin example, when execute userDao.deleteAllUsers(), we can not listen changes in UserActivity:

        disposable.add(viewModel.userName()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe({ this.user_name.text = it }, 
                        { error -> Log.e(TAG, "Unable to get username", error) }))

subscribe() will no be executed.