code: func getISCSISecretNameAndNamespace(spec *volume.Spec, defaultSecretNamespace string) (string, string, error) {
  	if spec.Volume != nil && spec.Volume.ISCSI != nil {
  		if spec.Volume.ISCSI.SecretRef != nil {
  			return spec.Volume.ISCSI.SecretRef.Name, defaultSecretNamespace, nil
  		}
  		return "", "", nil
  	} else if spec.PersistentVolume != nil &&
  		spec.PersistentVolume.Spec.ISCSI != nil {
  		secretRef := spec.PersistentVolume.Spec.ISCSI.SecretRef
  		secretNs := defaultSecretNamespace
  		if secretRef != nil {
  			if len(secretRef.Namespace) != 0 {
  				secretNs = secretRef.Namespace
  			}
  			return secretRef.Name, secretNs, nil
  		}
  		return "", "", nil
  	}
  
  	return "", "", fmt.Errorf("Spec does not reference an ISCSI volume type")
  }
docs: // get iSCSI CHAP Secret info: secret name and namespace