[keycloak-user] Swagger json reference

Hello keycloak users, I can't figure out how to generate the swagger json files that are mentioned there : https://blog.keycloak.org/2015/09/having-fun-with-rest-api-documentation.... I tried running that specific goal multiple times, but it always only gives me HTML. Swagger output would be more useful for writing my own clients in various languages, and more comfortable than parsing through HTML. Does anyone know how to get it? Thanks.