[atlas] [UDM creation API] Which parameters are mandatory?

It seems that in <https://atlas.ripe.net/doc/measurement-creation-api/> (now linked from the Atlas documentation so I assume it is no longer in alpha test), there is no mention of which properties are mandatory and which are not. I have to resort to trial-and-error. For instance, for DNS measurements, the property query_class appear to be mandatory (otherwise, I get an error 400) which is suprising (it defaults to IN in all the DNS clients I know).