ReST API for meta-data doesn't support JSON

While trying to figure out how the new meta-data DSL feature works, I found that the meta-data end-points on the ReST API v2 are not working with JSON.

Interestingly, the whole ReST API v2 defaults to JSON when the accept header is not specified (which is different from the v1 API, which is XML).

Only the meta-data end-points defaults to XML, the code mentions that JSON is an option, but the data is not shown (you get an empty array even if there are meta-data entries). This can be easily reproducible after setting the Accept header to be "application/json".