code: func (objMgr *ObjectManager) GetUpgradeStatus(statusType string) ([]UpgradeStatus, error) {
  	var res []UpgradeStatus
  
  	if statusType == "" {
  		// TODO option may vary according to the WAPI version, need to
  		// throw relevant  error.
  		msg := fmt.Sprintf("Status type can not be nil")
  		return res, errors.New(msg)
  	}
  	upgradestatus := NewUpgradeStatus(UpgradeStatus{Type: statusType})
  	err := objMgr.connector.GetObject(upgradestatus, "", &res)
  
  	return res, err
  }
docs: // GetUpgradeStatus returns the grid upgrade information