default Optional<ApplicationInstance> getApplicationNarrowedTo(HostName hostname) {
        return getApplication(hostname);
    }
Returns a ServiceModel which contains the current liveness status (up, down or unknown) of all instances
of all services of all clusters of all applications in a zone.

<p>Please use the more specific methods below to avoid the cost of this method.</p>
service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceMonitor.java