@Override
    public void deleteMember(String groupName, JID user)
    {
        if (isReadOnly()) {
            throw new UnsupportedOperationException("Cannot remove members from read-only groups");
        }
        synchronized (sharedGroupMetaCache) {
            sharedGroupMetaCache.clear();
        }
    }
@throws UnsupportedOperationException if the provider is read only
xmppserver/src/main/java/org/jivesoftware/openfire/group/AbstractGroupProvider.java