Hierarchy missing in ttl output?

**Is your feature request related to a problem? Please describe.**
A rest call, e.g. with "Accept" : "application/json" returns the class hierarchy while "Accept : "text/turtle" does not. Is there a particular reason that the response doesn't return the same content regardless of format?

**Describe the solution you'd like**
It seems as if the Dictionary schema allows for a "ParentClassCode". Eventhough a "ParentClassURI" would have been more useful (similar to rdfs:subClassOf), could "ParentClassCode" be a part of the response for a class URI? This way, at least the class hierarchy would be accessible in a linked data setting.

**Describe alternatives you've considered**
My knowledge of the API is limited right nowl, but I guess that one alternative would be to use the API, but, a simple access through URI:s is preferrable.

**Additional context**
application/json:

test/turtle: