presto-orc/src/main/java/io/prestosql/orc/metadata/statistics/StatisticsHasher.java/StatisticsHasher/putOptionalSlice
class StatisticsHasher:    public StatisticsHasher putOptionalSlice(Slice value)
    {
        hasher.putBoolean(value != null);
        if (value != null) {
            // there are better ways to do this, but values are limited to 64 bytes
            hasher.putBytes(value.getBytes());
        }
        return this;
    }