Error - empty type not parsed correctly in JSON format

I have controller master branch from 19th of March and I’m working with node of type empty.

The problem is with JSON format. Successful ways for PUT in JSON format are to put "link-status" : null according to this specification:

http://www.xml.com/lpt/a/1658

Get request retrieve always data this way "link-status" : "". But according to this specification:

https://tools.ietf.org/html/draft-lhotka-netmod-yang-json-02#section-3.3.9

we should PUT empty element this way "link-status" : [null] but I’m getting 400 bad request error:
"error-type": "protocol",
"error-tag": "malformed-message",
"error-message": "Error parsing input: Incorrect nesting caused by parser."

Could you please tell us if the second way is correct and if it's just not working or the right way is first option (w/o array)? The second question is if the respond data "link-status" : "" are correct.