code: public VsanUpgradeSystemPreflightCheckResult performVsanUpgradePreflightCheck(ClusterComputeResource cluster) throws RuntimeFault, VsanFault, RemoteException {
          return performVsanUpgradePreflightCheck(cluster, null);
      }
docs: Perform an upgrade pre-flight check on a cluster.
  
  @param cluster The cluster for which to perform the check.
  @return Pre-flight check result.
  @throws RuntimeFault
  @throws VsanFault
  @throws RemoteException