presto-rcfile/src/main/java/io/prestosql/rcfile/text/TimestampEncoding.java/TimestampEncoding/encodeValueInto
class TimestampEncoding:    @Override
    public void encodeValueInto(int depth, Block block, int position, SliceOutput output)
    {
        long millis = type.getLong(block, position);
        buffer.setLength(0);
        dateTimeFormatter.printTo(buffer, millis);
        for (int index = 0; index < buffer.length(); index++) {
            output.writeByte(buffer.charAt(index));
        }
    }