code: func (d *detacherDefaults) UnmountDevice(deviceMountPath string) error {
  	klog.Warning(logPrefix(d.plugin.flexVolumePlugin), "using default UnmountDevice for device mount path ", deviceMountPath)
  	return mount.CleanupMountPoint(deviceMountPath, d.plugin.host.GetMounter(d.plugin.GetPluginName()), false)
  }
docs: // UnmountDevice is part of the volume.Detacher interface.