Consider making odata the default namespace for annotations

If the client does not specify odata.maxversion = 4.0, the service may omit the "odata." namespace for annotations. Clients interpret properties starting with "@" that don't contain a dot as being within the odata namespace. i.e., "@type", "@id", "@editLink", "@nextLink", etc. Clients must still be prepared to receive results with the "odata." prefix and must only omit the prefix in request bodies to services supporting OData 4.01 or greater (generally, it should be safe to format a request body the same way it was retrieved in a response)