Custom onNext() implementation for RxJava and Retrofit - api

Question

I'm using RxJava alongside Retrofit and I'm trying to find a really clean way of abstracting my API calls in such a way that I can minimize code in the Activity.
So far, I have something like this:
Observable<SomeObservable> combined =
Observable.zip(firstObservable, secondObservable, SomeObservable::new);
// Works but needs header parsing
RxRestNetworker.performAsyncApiCall(combined, (returnData) -> {
// onNext() implementation
}, () -> hideSuggestionProgress());
The RxRestNetworker class looks like:
public class RxRestNetworker {
private static final String LOG_TAG = RxRestNetworker.class.getCanonicalName();
// Default error handling
private static Action1<Throwable> mOnError = throwable -> {
Log.e(LOG_TAG, throwable.getMessage());
throwable.printStackTrace();
};
/**
* Perform the desired request with default error handling
* #param observable
* #param onAction
* #param <T>
* #return
*/
public static <T> Subscription performAsyncApiCall(Observable<T> observable, Action1<? super T> onAction, Action0 onComplete) {
// Use default error handling
return performAsyncApiCall(observable, onAction, mOnError, onComplete);
}
/**
* Perform the desired request with some error handling OTHER than the default one
* #param observable
* #param onAction
* #param onError
* #param <T>
* #return
*/
public static <T> Subscription performAsyncApiCall(Observable<T> observable, Action1<? super T> onAction, Action1<Throwable> onError, Action0 onComplete) {
return observable.subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())
.subscribe(onAction, onError, onComplete);
}
}
So you can see I'm using the default onError() by calling the first performAsyncApiCall method.
Now this all works, but I need to access the headers of the response by getting access to the response object.
This post claimed that I should wrap my response object and declare it like so in the API:
Observable<Response<SomeResponse>> getThings();
But I don't really care for that. It seems ugly and makes zipping observables like above a headache.
Ideally, I'd like to create an abstraction of the onNext() Action1 argument that can by default log the headers and do anything else done for every API call, then pass the results of the call back to the caller. Am I going in the wrong direction with this? Can somebody please help me find a way to abstract this in a very clean manner?
Thank you!