presto-orc/src/main/java/io/prestosql/orc/metadata/statistics/StatisticsHasher.java/StatisticsHasher/putOptionalHashable
class StatisticsHasher:    public StatisticsHasher putOptionalHashable(Hashable value)
    {
        hasher.putBoolean(value != null);
        if (value != null) {
            value.addHash(this);
        }
        return this;
    }