Marking functions as deprecated in JSON

I would like to declare several functions in my JSON-based API description as deprecated, so that the editor can visualize this properly (like using a strike-through text). From looking at the code, this seems still unsupported? Or is there a suggested approach?
Maybe some additional marker like “!deprecated” would be useful?

I don’t want to keep adding support for more ! markers, but one possible avenue to do this in a clean way would be to use the existing (though not very well-tested) !data marker, which corresponds to teh metaData property on the actual data structure, to store this. This is currently not used in query responses, but we could make it so that, for a "type" query, if the resulting type has metadata, that is returned in the response object. You could then have your deprecated flag be a property of the metadata object.