@Override
    public final void writeDateYYYMMDD8(int year, int month, int dayOfMonth) {
        int off = this.off;
        int minCapacity = off + 10;
        byte[] bytes = this.bytes;
        if (minCapacity > bytes.length) {
            bytes = grow(minCapacity);
        }
        bytes[off] = (byte) quote;
        if (year < 0 || year > 9999) {
            throw illegalYear(year);
        }
        int y01 = year / 100;
        int y23 = year - y01 * 100;
        writeDigitPair(bytes, off + 1, y01);
        writeDigitPair(bytes, off + 3, y23);
        writeDigitPair(bytes, off + 5, month);
        writeDigitPair(bytes, off + 7, dayOfMonth);
        bytes[off + 9] = (byte) quote;
        this.off = off + 10;
    }
A faster alternative that is functionally equivalent to Long.expand(i, 0x0F0F_0F0F_0F0F_0F0FL)
core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF8.java