code: public VsanUpgradeSystemUpgradeStatus queryVsanUpgradeStatus(ClusterComputeResource cluster) throws RuntimeFault, VsanFault, RemoteException {
          return getVimService().queryVsanUpgradeStatus(getMOR(), cluster.getMOR());
      }
docs: Retrieve the latest status of a running, or the previously completed, upgrade process. Information about previous
  upgrade runs are not always, e.g. when VC gets restarted.
  
  @param cluster The cluster for which to retrieve the upgrade status.
  @return Status
  @throws RuntimeFault
  @throws VsanFault
  @throws RemoteException