public static function getXDomainUserId($domain_username, $domain)
	{
		$db = \App::get('db');

		if (empty($domain) || ($domain == 'hubzero'))
		{
			return $domain_username;
		}

		$query = 'SELECT uidNumber FROM #__xdomain_users,#__xdomains WHERE ' .
				 '#__xdomains.domain_id=#__xdomain_users.domain_id AND ' .
				 '#__xdomains.domain=' . $db->quote($domain) . ' AND ' .
				 '#__xdomain_users.domain_username=' . $db->quote($domain_username);
		$db->setQuery($query);

		$result = $db->loadObject();

		if (empty($result))
		{
			return false;
		}

		return $result->uidNumber;
	}