Simplest way to retain an active Observable during configuration changes

RetainedObservableActivity.java

package me.eugeniomarletti.example;

import android.app.Activity;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.widget.Toast;
import rx.Observable;
import rx.Subscriber;
import rx.Subscription;
import rx.android.schedulers.AndroidSchedulers;

import java.util.concurrent.TimeUnit;

public class RetainedObservableActivity extends Activity {

    @Nullable
    private Observable<String> observable;

    @Nullable
    private Subscription subscription;

    @NonNull
    private static Observable<String> observableFactory() {
        // just an example
        return Observable
                .interval(0, 1, TimeUnit.SECONDS)
                .take(10)
                .map(String::valueOf);
    }

    @NonNull
    private static Observable<String> createCachedObservable() {
        return observableFactory()
                .observeOn(AndroidSchedulers.mainThread())
                .replay(1)
                .autoConnect();
    }

    @NonNull
    private Observable<String> getOrCreateObservable() {
        Observable<String> observable = this.observable;
        if (observable == null) {
            observable = createCachedObservable();
            this.observable = observable;
        }
        return observable;
    }

    private void resetObservable() {
        this.observable = null;
        unsubscribe();
    }

    private void unsubscribe() {
        if (subscription != null) {
            subscription.unsubscribe();
            subscription = null;
        }
    }

    private void subscribe() {
        if (subscription == null || subscription.isUnsubscribed()) {
            subscription = getOrCreateObservable().subscribe(new Subscriber<String>() {
                @Override
                public void onNext(String s) {
                    Toast.makeText(RetainedObservableActivity.this, s, Toast.LENGTH_SHORT).show();
                }

                @Override
                public void onCompleted() {
                    Toast.makeText(RetainedObservableActivity.this, "COMPLETED", Toast.LENGTH_SHORT).show();
                    resetObservable();
                }

                @Override
                public void onError(Throwable e) {
                    Toast.makeText(RetainedObservableActivity.this, "ERROR", Toast.LENGTH_SHORT).show();
                    resetObservable();
                }
            });
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        observable = getLastNonConfigurationInstance();
        subscribe();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unsubscribe();
    }

    @Override
    @SuppressWarnings("deprecation") // safe to use
    public Object onRetainNonConfigurationInstance() {
        return observable;
    }

    @Nullable
    @Override
    @SuppressWarnings("deprecation") // safe to use
    public Observable<String> getLastNonConfigurationInstance() {
        //noinspection unchecked // we always pass the same thing in this example
        return (Observable<String>)super.getLastNonConfigurationInstance();
    }
}