title: combineLatest() function on mainThread
body: <p>I want to combine 2 observables and execute "combine function" on AndroidSchedules.mainThread(). I've added .observeOn(AndroidSchedules.mainThread()) but I am still getting "java.lang.IllegalStateException: Not on the main thread".</p>
  
  <pre><code>Observable&lt;List&lt;Post&gt;&gt; animateCameraAndGetPostsByProjection = Observable.combineLatest(
              mapObservableProvider.getMapReadyObservable(),
              LocationService.getUpdatedOrLastKnownLocation(this),
              (googleMap, location) -&gt; {
                  CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(),location.getLongitude()),15);
                  googleMap.moveCamera(cameraUpdate);
                  return googleMap.getProjection().getVisibleRegion();
              })
              .flatMap(vr -&gt; new RestService().getApi().getPostsByMapProjection(vr.farLeft.latitude,vr.farLeft.longitude,vr.nearRight.latitude,vr.nearRight.longitude))
              .observeOn(AndroidSchedulers.mainThread());
  </code></pre>