@Override
    public void updateMember(String groupName, JID user, boolean administrator) throws GroupNotFoundException
    {
        final Group group = data.get(groupName);
        if (group == null) {
            throw new GroupNotFoundException();
        }
        (administrator ? group.getAdmins() : group.getMembers()).add(user);
        (!administrator ? group.getAdmins() : group.getMembers()).remove(user);
    }
A very basic implementation of a GroupProvider, that retains data in-memory.

@author Guus der Kinderen, guus@goodbytes.nl
xmppserver/src/test/java/org/jivesoftware/openfire/group/TestGroupProvider.java