@Override
    public Set<ApplicationId> getAllSuspendedApplications() {
        Set<ApplicationInstanceReference> refSet = statusService.getAllSuspendedApplications();
        return refSet.stream().map(OrchestratorUtil::toApplicationId).collect(toSet());
    }
Suspend normal operations for a group of nodes in the same application.

@param nodeGroup The group of nodes in an application.
@throws HostStateChangeDeniedException if the request cannot be met due to policy constraints.
orchestrator/src/main/java/com/yahoo/vespa/orchestrator/OrchestratorImpl.java