@Override
    public final void writeLocalDateTime(LocalDateTime dateTime) {
        int off = this.off;
        int minCapacity = off + 38;
        byte[] bytes = this.bytes;
        if (minCapacity > bytes.length) {
            bytes = grow(minCapacity);
        }
        bytes[off++] = (byte) quote;
        LocalDate localDate = dateTime.toLocalDate();
        off = IOUtils.writeLocalDate(bytes, off, localDate.getYear(), localDate.getMonthValue(), localDate.getDayOfMonth());
        bytes[off++] = ' ';
        off = IOUtils.writeLocalTime(bytes, off, dateTime.toLocalTime());
        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