presto-parquet/src/main/java/io/prestosql/parquet/ParquetTimestampUtils.java/ParquetTimestampUtils/julianDayToMillis
class ParquetTimestampUtils:    private static long julianDayToMillis(int julianDay)
    {
        return (julianDay - JULIAN_EPOCH_OFFSET_DAYS) * MILLIS_IN_DAY;
    }