Requested feature from the YooChoose side:

Is it possible to add the contentTypeId in the event, meaning POSTing sth. like.

 "transaction" : "",
 "events" : [
   {
     "action" : "UPDATE",
     "uri" : "\/api\/ezp\/v2\/content\/objects\/58",
     “contentTypeId” : 16
       }
 ]
}

It’d save a lot of work on my side