public abstract UserPrincipalLookupService getUserPrincipalLookupService ()

Returns the UserPrincipalLookupService for this file system (optional operation). The resulting lookup service may be used to lookup user or group names.

Usage Example: Suppose we want to make "joe" the owner of a file:

     UserPrincipalLookupService lookupService = FileSystems.getDefault().getUserPrincipalLookupService();
     Files.setOwner(path, lookupService.lookupPrincipalByName("joe"));
 

Returns:  The UserPrincipalLookupService for this file system

Exceptions:
UnsupportedOperationException     If this FileSystem does not does have a lookup service