a different approach to make tracing compatible with transformDeferredContextual operator

[bruto1]

No description provided.

[jam01]

Hey @bruto1 sorry for the delay, obviously the ot project has been on maintenance mode with the advent of otel, plus I haven't been working with reactor for a couple of years now.

As far as your implementation, to me it seems it serves a different purpose than what we have currently. The current is a way to instrument every operator in the chain so a span is open for use by some other computation, a db or http call for example. Your implementation seems more aimed at targeting discrete operators and also opening a new span for it, which we couldn't do with the other approach.

So I don't think I can merge this is in its current form. But perhaps if you're interested in making it work as another option alongside the current implementation then I think that'd be ok.

[bruto1]

I learned about OTel after doing this myself, guess the fix would come in handier there
Maybe I'll get around to figuring out their more complicated API and adapting this fix for that project

FWIW, this impl only came about because the existing one wasn't adequate for our needs.
Never saw the advantage of a dotted span vs. uninterrupted subscription-to-termination and then there's this missing propagation of span upstream at subscription time.
Figured I'd make it they way I like :)