String toUrl(ConfigKey<?> key, boolean rec) {
            return urlBase + key.getNamespace() + "." + key.getName() + "/" + key.getConfigId() + (rec ? "" : "/");
        }
The listing URL for this config in this service

@param key config key
@param rec recursive
@return url
configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpListConfigsHandler.java