Sigh, xml hard at work solving a problem we never seen, but creates such a bloted horrible mess where json would have been simple and better.
The downside is it has to be pretty complicated to enable the magic, so building it can be complicated, and debugging it is a nightmare. You could say the same about a lot of modern JS, and that's been somewhat solved by amazing tooling.
In my data oriented mind, the primary thing that matters is the data that is sent, the second is other semantics like idempotency.
Neither SOAP nor XML solve or helps: there might be no wsdl bindings in your language, or they are badly implemented (true in my experience).
XML make people nest structures where it could have been flatter, SOAP even more, and annotates everything whithout a need for that.
This cost for no reason but to entertain the CORBA like pipe dream, or should I say nightmare.
We just resorted to pulling out data from xml with xpath. And more or less template the response back, no wsdl and very simple.
But why inflict this pain on your API users?
please think through your API if you are to design an API, the tools will not think for you and you can fool yourself instead...
Swagger will not magically solve anything. I have seen and experienced that you can really create nonsensical but pretty and auto documented APIs using swagger in no time.