Java compact1, compact2, compact3 java.nio.file.attribute Interface GroupPrincipal（JDK8）

public interface GroupPrincipal
extends UserPrincipal

A UserPrincipal representing a group identity, used to determine access rights to objects in a file system. The exact definition of a group is implementation specific, but typically, it represents an identity created for administrative purposes so as to determine the access rights for the members of the group. Whether an entity can be a member of multiple groups, and whether groups can be nested, are implementation specified and therefore not specified.