presto-orc/src/main/java/io/prestosql/orc/metadata/statistics/StringStatistics.java/StringStatistics/toString
class StringStatistics:    @Override
    public String toString()
    {
        return toStringHelper(this)
                .add("min", minimum == null ? "<null>" : minimum.toStringUtf8())
                .add("max", maximum == null ? "<null>" : maximum.toStringUtf8())
                .add("sum", sum)
                .toString();
    }