@Override
    public String toString() {
        return "KVOperation{" + "key=" + BytesUtil.toHex(key) + ", value=" + BytesUtil.toHex(value) + ", attach="
               + attach + ", op=" + op + '}';
    }
The best practice is to call this method only once
and keep a copy of it yourself.
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/storage/KVOperation.java