Rxで非同期処理とプログレス表示切り替えを分離する

public class FooFragment extends Fragment {

    FragmentFooBinding dataBinding;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        dataBinding = DataBindingUtil.inflate(inflater, R.layout.fragment_foo, container, false);

        // adapterとかの初期化

        dataBinding.swipeRefreshLayout.setOnRefreshListener(() -> {
            refresh().subscribe(dataBinding.swipeRefreshLayout::setRefreshing);
        });

        return dataBinding.getRoot();
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        refresh().subscribe(loading -> {
            dataBinding.progress.setVisibility(loading ? View.VISIBLE : View.GONE);
        });
    }

    private Subject<Boolean> refresh() {
        Subject<Boolean> loadingSubject = BehaviorSubject.create();

        mApiService.topics()
                .compose(bindUntilEvent(FragmentEvent.DESTROY_VIEW))
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .doOnSubscribe(disposable -> loadingSubject.onNext(true))
                .doFinally(() -> loadingSubject.onNext(false))
                .subscribe(
                        response -> {
                            adapter.setData(response.topics);
                        },
                        throwable -> Log.e(TAG, "fetch: ", throwable)
                );

        return loadingSubject;
    }
}