@Override
    public final String toString() {
        return new String(bytes, 0, off, StandardCharsets.UTF_8);
    }
A faster alternative that is functionally equivalent to Long.expand(i, 0x0F0F_0F0F_0F0F_0F0FL)
core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF8.java