RxJava adjust backpressure avoiding observeOn buffer - reactive-programming

Question

In the code below I would like the subscriber to control when the Flowable emits an event by holding a reference to the Subscription inside subscribe() and requesting the number of elements I want to be produced.
What I am experiencing is that observeOn()'s buffer with size 2 is hiding my call to subscription.request(3) as the producer is producing 2 elements at a time instead of 3.
public class FlowableExamples {
public static void main(String[] args) throws InterruptedException {
long start = new Date().getTime();
Flowable<Integer> flowable = Flowable
.generate(() -> 0, (Integer state, Emitter<Integer> emitter) -> {
int newValue = state + 1;
log("Producing: " + newValue);
emitter.onNext(newValue);
return newValue;
})
.take(30);
flowable
.subscribeOn(Schedulers.io())
.observeOn(Schedulers.computation(), false, 2)
.subscribe(new Subscriber<Integer>() {
Subscription subscription;
#Override
public void onSubscribe(Subscription subscription) {
this.subscription = subscription;
subscription.request(5);
}
#Override
public void onNext(Integer integer) {
log("\t\treceived: " + integer);
if (integer >= 5) {
sleep(500);
log("Requesting 3 should produce 3, but actually produced 2");
subscription.request(3);
sleep(1000);
}
}
#Override
public void onError(Throwable throwable) {}
#Override
public void onComplete() {
log("Subscription Completed!!!!!!!!");
}
});
sleep(40_000);
System.out.println("Exit main after: " + (new Date().getTime() - start) + " ms");
}
private static void log(String msg) {
System.out.println(Thread.currentThread().getName() + ": " + msg);
}
private static void sleep(long ms) {
try {
Thread.sleep(ms);
} catch (InterruptedException e) {}
}
}
How could I accomplish this?