[keycloak-user] Server Initialization: Is there a REST API to create the first/initial admin user

[keycloak demo]

Can the first admin user be created through a REST API?

The doc
https://www.keycloak.org/docs/4.3/server_admin/index.html#server-initialization
mentions
that first admin can be created either  by : http://localhost:8080/auth URL
or with add-user-keycloak  script. Is adding first admin possible through a
REST API?