@Override
    public Directory<UserGroup> getUserGroupDirectory()
            throws GuacamoleException {
        return new SimpleDirectory<UserGroup>();
    }
{@inheritDoc}

<p>This implementation simply returns an empty {@link Directory}.
Implementations that wish to expose user groups should override this
function.
guacamole-ext/src/main/java/org/apache/guacamole/net/auth/AbstractUserContext.java