rtslib.target.Group:
An abstract base class akin to CFSNode, but for classes that
emulate a higher-level group object across the actual NodeACL
configfs structure.
rtslib.target.MappedLUNGroup:
Used with NodeACLGroup, this aggregates all MappedLUNs with the
same LUN so that it can be configured across all members of the
NodeACLGroup.