@Override
    public final void writeInt64(Long i) {
        if (i == null) {
            writeNumberNull();
        } else {
            writeInt64(i.longValue());
        }
    }
A faster alternative that is functionally equivalent to Long.expand(i, 0x0F0F_0F0F_0F0F_0F0FL)
core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF8.java