@Override
    public void removeApplication(ApplicationInstanceReference reference) {
        ApplicationId application = OrchestratorUtil.toApplicationId(reference);
        curator.delete(Path.fromString(applicationPath(application)));
    }
Handles all ZooKeeper data structures related to each active application, including HostInfo.
Cache (if any) is above and not visible here.

@author hakonhall
orchestrator/src/main/java/com/yahoo/vespa/orchestrator/status/HostInfosServiceImpl.java