org.w3c.dom.DOMException:HIERARCHY_REQUEST_ERR

我一直在寻找太长的时间,无法弄清楚我做错了什么.

所以,我正在尝试为某些内容生成Xades签名.不幸的是我总是遇到同样的错误:"HIERARCHY_REQUEST_ERR".这是我的XML文档:

我正在尝试使用以下代码签署"Request"元素(显然......):

/*create a document*/
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
Document doc = docBuilder.newDocument();
Element objectElement = doc.createElement("object");
doc.appendChild(objectElement);
Element requestElement = doc.createElement("request");
requestElement.appendChild(doc.createTextNode(decodedContent));
requestElement.setAttribute("id", UUID.randomUUID().toString());
objectElement.appendChild(requestElement);

/*Key provider, signing profile & signer itself*/
KeyingDataProvider kp = new CustomKeyingDataProvider(certificate, privateKey);
XadesSigningProfile p = new XadesTSigningProfile(kp);
XadesSigner signer = p.newSigner();

/*Signed data*/
DataObjectDesc flatFile = new DataObjectReference("#" + requestElement.getAttribute("id"))
    .withTransform(new GenericAlgorithm("http://www.w3.org/2000/09/xmldsig#base64"))
    .withDataObjectTimeStamp();
SignedDataObjects dataObjs = new SignedDataObjects(flatFile).withCommitmentType(AllDataObjsCommitmentTypeProperty.proofOfOrigin());

/*Actual signing*/
signer.sign(dataObjs, doc);

我得到了这个错误(缩写为必要的):

class org.w3c.dom.DOMException: org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR: An    
attempt was made to insert a node where it is not permitted. 
    at org.apache.xerces.dom.CoreDocumentImpl.insertBefore(Unknown Source)
    at org.apache.xerces.dom.NodeImpl.appendChild(Unknown Source)
    at xades4j.production.AppendAsLastChildStrategy.append(SignatureAppendingStrategies.java:55)
    at xades4j.production.SignerBES.sign(SignerBES.java:210)
    at xades4j.production.SignerBES.sign(SignerBES.java:122)
    ...

我搜索了网络,但我发现的唯一类似错误就是这个:https://code.google.com/p/xades4j/wiki/QeA(几乎在顶部).我无法真正找到他的问题的答案,但据我所知,我的XML文档是一个根元素(就像他的第二个例子).所以我真的不知道我做错了什么......

有没有人能帮助我？提前致谢.