private static String createUrlStringFromId(String urlBase, ApplicationId id, Zone zone) {
        StringBuilder sb = new StringBuilder();
        sb.append(urlBase).append(id.application().value());
        sb.append("/environment/").append(zone.environment().value());
        sb.append("/region/").append(zone.region().value());
        sb.append("/instance/").append(id.instance().value());
        return sb.toString();
    }
Handler for listing currently active applications for a tenant.

@author Ulf Lilleengen
configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/ListApplicationsHandler.java