pub fn release_group(response: &Json) -> Option<Candidate<ReleaseFacts>>Expand description
One release group, as a lookup answers: /ws/2/release-group/<mbid>.
The counterpart of artist: an answer about the identifier that was
asked for is a certainty, where a search result is a guess with a score.
Used when the tags carry MUSICBRAINZ_RELEASEGROUPID but no edition.