Set<String> getInvisibleSharedGroupsNames() {
        return invisibleSharedGroups;
    }
Returns the invisible shared groups for the item. These groups are for internal use
and help track the reason why a roster item has a presence subscription of type FROM
when using shared groups.

@return The shared groups this item belongs to.
xmppserver/src/main/java/org/jivesoftware/openfire/roster/RosterItem.java