private void groupUserAdded(Group group, JID addedUser) {
        groupUserAdded(group, getAffectedUsers(group), addedUser);
    }
Notification that a Group user has been added. Update the group users' roster accordingly.

@param group the group where the user was added.
@param addedUser the username of the user that has been added to the group.
xmppserver/src/main/java/org/jivesoftware/openfire/roster/RosterManager.java