@Override
    public final void writeOffsetDateTime(OffsetDateTime dateTime) {
        if (dateTime == null) {
            writeNull();
            return;
        }

        int off = this.off;
        int minCapacity = off + 45;
        byte[] bytes = this.bytes;
        if (minCapacity > bytes.length) {
            bytes = grow(minCapacity);
        }
        bytes[off] = (byte) quote;
        LocalDateTime ldt = dateTime.toLocalDateTime();
        LocalDate date = ldt.toLocalDate();
        off = IOUtils.writeLocalDate(bytes, off + 1, date.getYear(), date.getMonthValue(), date.getDayOfMonth());
        bytes[off] = 'T';
        off = IOUtils.writeLocalTime(bytes, off + 1, ldt.toLocalTime());

        ZoneOffset offset = dateTime.getOffset();
        if (offset.getTotalSeconds() == 0) {
            bytes[off++] = 'Z';
        } else {
            String zoneId = offset.getId();
            zoneId.getBytes(0, zoneId.length(), bytes, off);
            off += zoneId.length();
        }
        bytes[off] = (byte) quote;
        this.off = off + 1;
    }
A faster alternative that is functionally equivalent to Long.expand(i, 0x0F0F_0F0F_0F0F_0F0FL)
core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF8.java