There's multiple different ways to author a multispanprocessor, with regards to the behavior of teeing to multiple downstream ones:
- synchronously, doing it one at a time
- concurrently, doing one or more in a threadpool or other concurrent executor.
I think it's probably good to start clarifying that early, so that consumes can choose which one works for their purposes. To that end, we should rename MultiSpanProcessor to SynchronousMultiSpanProcessor.