CIMRestService::recentUnread

static function recentUnread($arParams, $n, CRestServer $server)
{
	$arParams = array_change_key_case($arParams, CASE_UPPER);

	if ($arParams['DIALOG_ID'] !== 'notify' && !BitrixImCommon::isDialogId($arParams['DIALOG_ID']))
	{
		throw new BitrixRestRestException("Dialog ID can't be empty", "DIALOG_ID_EMPTY", CRestServer::STATUS_WRONG_REQUEST);
	}

	if (isset($arParams['ACTION']))
	{
		$arParams['UNREAD'] = $arParams['ACTION'];
	}

	return BitrixImRecent::unread($arParams['DIALOG_ID'], $arParams['UNREAD'] !== 'N');
}