6a380c4d19
The `aggregatorFunction` has a flaw subscribing and emitting data from a source `Flux` too early: from a `doOnSubscribe()` callback which is really called *before* the real subscription is registered in the target `Publisher` Change the logic to the `doOnRequest()` which happens already after subscription is registered in the `Publisher` **Cherry-pick to `2020.0.x`**