presto-main/src/main/java/io/prestosql/operator/scalar/DateTimeFunctions.java/DateTimeFunctions/currentTime
class DateTimeFunctions:    @Description("current time with time zone")
    @ScalarFunction
    @SqlType(StandardTypes.TIME_WITH_TIME_ZONE)
    public static long currentTime(ConnectorSession session)
    {
        // We do all calculation in UTC, as session.getStartTime() is in UTC
        // and we need to have UTC millis for packDateTimeWithZone
        long millis = UTC_CHRONOLOGY.millisOfDay().get(session.getStartTime());

        if (!session.isLegacyTimestamp()) {
            // However, those UTC millis are pointing to the correct UTC timestamp
            // Our TIME WITH TIME ZONE representation does use UTC 1970-01-01 representation
            // So we have to hack here in order to get valid representation
            // of TIME WITH TIME ZONE
            millis -= valueToSessionTimeZoneOffsetDiff(session.getStartTime(), getDateTimeZone(session.getTimeZoneKey()));
        }
        return packDateTimeWithZone(millis, session.getTimeZoneKey());
    }