错误回调中的Rxjava Flowable Access元素

Question

我有此代码：

    Flowable.fromIterable(references)
            .parallel() // you can also specify number of rails here
            .runOn(Schedulers.computation())
            .map(this.service::uploadImages)
            .sequential()
            .subscribe(
                    response -> processResponse(response),
                    error -> processError(error)
            );

我希望能够获取在processError中引起错误的元素？