ODATA-1323 clarified how term JSON.Schema shall be annotated. It says:

"

 [Use] a constant string expression for Edm.Stream with media types application/json or text/*

[...]

For stream values the annotation (property) MUST be annotated with term Core.MediaType and the media type of the stream as its value.

"

The latter statement is not yet reflected in the term definition of JSON.Schema