REST vocabulary information returns badly formatted languages

[osma]

At which URL did you encounter the problem?

http://localhost/Skosmos/rest/v1/yso/

What steps will reproduce the problem?

1. call the REST vocabulary information method for a vocabulary with many languages

What is the expected output? What do you see instead?

Expected to get a list of language tags, e.g.

"languages": ["fi","sv","en"]

Instead getting

"languages": {
    "englanti": "en",
    "ruotsi": "sv",
    "suomi": "fi"
},

This still worked in Skosmos 1.0 but was broken starting from 1.1