An event bus made with RxJava and RxAndroid

RxBus.java

/**
 * Used for subscribing to and publishing to subjects. Allowing you to send data between activities, fragments, etc.
 * <p>
 * Created by Pierce Zaifman on 2017-01-02.
 */

public final class RxBus {

    private static SparseArray<PublishSubject<Object>> sSubjectMap = new SparseArray<>();
    private static Map<Object, CompositeDisposable> sSubscriptionsMap = new HashMap<>();

    public static final int SUBJECT_MY_SUBJECT = 0;
    public static final int SUBJECT_ANOTHER_SUBJECT = 1;

    @Retention(SOURCE)
    @IntDef({SUBJECT_MY_SUBJECT, SUBJECT_ANOTHER_SUBJECT})
    @interface Subject {
    }

    private RxBus() {
        // hidden constructor
    }

    /**
     * Get the subject or create it if it's not already in memory.
     */
    @NonNull
    private static PublishSubject<Object> getSubject(@Subject int subjectCode) {
        PublishSubject<Object> subject = sSubjectMap.get(subjectCode);
        if (subject == null) {
            subject = PublishSubject.create();
            subject.subscribeOn(AndroidSchedulers.mainThread());
            sSubjectMap.put(subjectCode, subject);
        }

        return subject;
    }

    /**
     * Get the CompositeDisposable or create it if it's not already in memory.
     */
    @NonNull
    private static CompositeDisposable getCompositeDisposable(@NonNull Object object) {
        CompositeDisposable compositeDisposable = sSubscriptionsMap.get(object);
        if (compositeDisposable == null) {
            compositeDisposable = new CompositeDisposable();
            sSubscriptionsMap.put(object, compositeDisposable);
        }

        return compositeDisposable;
    }

    /**
     * Subscribe to the specified subject and listen for updates on that subject. Pass in an object to associate
     * your registration with, so that you can unsubscribe later.
     * <br/><br/>
     * <b>Note:</b> Make sure to call {@link RxBus#unregister(Object)} to avoid memory leaks.
     */
    public static void subscribe(@Subject int subject, @NonNull Object lifecycle, @NonNull Consumer<Object> action) {
        Disposable disposable = getSubject(subject).subscribe(action);
        getCompositeDisposable(lifecycle).add(disposable);
    }

    /**
     * Unregisters this object from the bus, removing all subscriptions.
     * This should be called when the object is going to go out of memory.
     */
    public static void unregister(@NonNull Object lifecycle) {
        //We have to remove the composition from the map, because once you dispose it can't be used anymore
        CompositeDisposable compositeDisposable = sSubscriptionsMap.remove(lifecycle);
        if (compositeDisposable != null) {
            compositeDisposable.dispose();
        }
    }

    /**
     * Publish an object to the specified subject for all subscribers of that subject.
     */
    public static void publish(@Subject int subject, @NonNull Object message) {
        getSubject(subject).onNext(message);
    }
}

could you add imports on source? i cant use that