code: public void importUnmanagedSnapshot(String vdisk, Datacenter datacenter, String vvolId) throws InvalidDatastore, NotFound, RuntimeFault, RemoteException {
          getVimService().importUnmanagedSnapshot(getMOR(), vdisk, datacenter == null ? null : datacenter.getMOR(), vvolId);
      }
docs: Import an unmanaged-snapshot from Virtual-Volume(VVol) enabled Storage Array.
  <p>
  Storage Array may support users to take snapshots indepedent of VMware stack. Such copies or snapshots are known
  as 'Unmanaged-Snapshots'. We are providing an ability to end-users to import such unmanaged-snapshots as Virtual
  Disks.
  <p>
  End-user needs to know the VVol-Identifier to import unmanaged snapshot as VirtualDisk.
  <p>
  Once VirtualDisk is created, user can use 'Datastore Browser' to use with rest of Virtual Machine provisioning
  APIs.
  
  @param vdisk      -
  The name of the disk to import, either a datastore path or a URL referring to the virtual disk from
  which to get geometry information.
  @param datacenter -
  If vdisk is a datastore path, the datacenter for that datastore path. Not needed when invoked
  directly on ESX. If not specified on a call to VirtualCenter, vdisk must be a URL.
  @param vvolId     Unmanaged snapshot identifier
  @throws InvalidDatastore
  @throws NotFound
  @throws RuntimeFault
  @throws RemoteException
  @since 6.0