CCalendar::FindSyncInstance

static function FindSyncInstance($event)
{
	$exchangeScheme = COption::GetOptionString('dav', 'exchange_scheme', 'http');
	$exchangeServer = COption::GetOptionString('dav', 'exchange_server', '');
	$exchangePort = COption::GetOptionString('dav', 'exchange_port', '80');
	$exchangeUsername = COption::GetOptionString('dav', 'exchange_username', '');
	$exchangePassword = COption::GetOptionString('dav', 'exchange_password', '');

	if (empty($exchangeServer))
	{
		return '';
	}

	$exchange = new CDavExchangeCalendar($exchangeScheme, $exchangeServer, $exchangePort, $exchangeUsername, $exchangePassword);

	$params = [
		'dateTo' => $event['DATE_TO'],
		'parentDateTo' => $event['DATE_TO'],
		'dateFrom' => $event['DATE_FROM'],
		'parentDateFrom' => $event['DATE_FROM'],
		'parentTz' => $event['TZ_FROM'],
		'changekey' => $event['DAV_EXCH_LABEL'],
	];

	[ , $changeKey] = $exchange->FindInstance($params);

	return $changeKey;
}