code: func GetFullQualifiedPluginNameForVolume(pluginName string, spec *volume.Spec) string {
  	if spec != nil && spec.PersistentVolume != nil && spec.PersistentVolume.Spec.CSI != nil {
  		return fmt.Sprintf("%s:%s", pluginName, spec.PersistentVolume.Spec.CSI.Driver)
  	}
  	return pluginName
  }
docs: // GetFullQualifiedPluginNameForVolume returns full qualified plugin name for
  // given volume. For CSI plugin, it appends plugin driver name at the end of
  // plugin name, e.g. kubernetes.io/csi:csi-hostpath. It helps to distinguish
  // between metrics emitted for CSI volumes which may be handled by different
  // CSI plugin drivers.