Get value in UDF dynamically

Question

Hi Gurus,
I have an importstructure which can be enhanced dynamiccaly hence not all fields are defined and available in the mapping. Now there is a field which is not defined in the importstructure that contains a value I want to read.
I'm trying to create an UDF which reads a value from a structure dynamically. The path of this field is given as an inputparameter (KVK).
public String Bepaal(Container container) throws StreamTransformationException{
Document doc = null;
String value = null;
try {
    String inParam = container.getInputParameters().getString("KVK");
    //Bouw document op o.b.v. intpustream
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setNamespaceAware(false);
    DocumentBuilder builder = factory.newDocumentBuilder();
    doc = builder.parse(<How do I get the inputstream??>);
    //Bouw xpath expressie t.b.v. het ophalen van de base64 gecodeerde waarde
    XPathFactory xFactory = XPathFactory.newInstance();
    XPath xpathExpr = xFactory.newXPath();
    XPathExpression expr = xpathExpr.compile(inParam);
    Object result = expr.evaluate(doc, XPathConstants.NODESET);
    //Bepaal gevonden node(s) en bepaal de waarde van de eerstgevonden waarde in de lijst
    NodeList nlList = (NodeList) result;
    value = nlList.item(0).getNodeValue();
catch (Exception e) {
    container.getTrace().addWarning(e.toString());
    return "";
return value;
return value
The problem is, how do I get the inputstream? I only have a container element.

Answer 1

Thanks, this is somewhat helpfull but the field I need is a but more difficult to find, it is not unique.
I need the value in field IdValue where idOwner = "KvK".
Is this possible?
<AdditionalData>
    <StaffingAdditionalData>
      <CustomerReportingRequirements>
        <PurchaseOrderNumber>4357435</PurchaseOrderNumber>
        <CustomerReferenceNumber>43545453443</CustomerReferenceNumber>
        <PurchaseOrderLineItem>00001</PurchaseOrderLineItem>
      </CustomerReportingRequirements>
      <ReferenceInformation>
        <OrderId idOwner="StaffingCustomer">
          <IdValue>546576653</IdValue>
        </OrderId>
        <StaffingSupplierId idOwner="StaffingCustomer">
          <IdValue>346554</IdValue>
        </StaffingSupplierId>
        <StaffingSupplierId idOwner="KvK">
          <IdValue>547365737635</IdValue>
        </StaffingSupplierId>
        <StaffingCustomerId idOwner="StaffingCustomer">
          <IdValue>FC70</IdValue>
        </StaffingCustomerId>
        <StaffingCustomerId idOwner="OIN">
          <IdValue>57645654646</IdValue>
        </StaffingCustomerId>
      </ReferenceInformation>
    </StaffingAdditionalData>
  </AdditionalData>