Updating to 8.15.1 form 8.12.1 and I've noticed the Hit class is id field is now nullable? Why? Is it possible to have docs without and ID? How does that even work?
I did not check but may be it's related to the changes that are happening with the new index mode logsdb?
I'm not sure though 
Hello! It's a very specific case: when stored_fields is set to none on a search request, the result contains no _id field. More info on store here in the docs.