presto-rcfile/src/main/java/io/prestosql/rcfile/text/TimestampEncoding.java/TimestampEncoding/encodeColumn
class TimestampEncoding:    @Override
    public void encodeColumn(Block block, SliceOutput output, EncodeOutput encodeOutput)
    {
        for (int position = 0; position < block.getPositionCount(); position++) {
            if (block.isNull(position)) {
                output.writeBytes(nullSequence);
            }
            else {
                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));
                }
            }
            encodeOutput.closeEntry();
        }
    }