ChainApi3.kt

fun cacheApi1AndZipApi2(): Observable<Pair<Media, okhttp3.Response>> {
    val api1: Observable<Response<Media>> = Api.api1().cache()
    return api1.flatMap { response ->
        if (response.isSuccessful) {
            var uploadUrl = response.headers().get(ApiUtils.Header.LOCATION)
            uploadUrl?.let { url ->
                Api.api2(url).zipWith(api1) { r2, r1 -> Pair(r1.body(), r2) }
            } ?: run {
                throw Exceptions.propagate(NullPointerException("Media upload URL is empty"))
            }
        } else
            Observable.error(ApiRequestException(response))
    }
}