title: Descriptor with default root element was not found in the project jaxb unmarshall
body: <p>I have the root element in my xml file as follows:</p>
  
  <pre><code>&lt;Document xmlns="urn:kad:ns:file:1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"&gt;
  </code></pre>
  
  <p>and the XSD header is as follows:</p>
  
  <pre><code> &lt;xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" 
  targetNamespace="urn:kad:ns:file:1" xmlns:xs="http://www.w3.org/2001/XMLSchema"&gt;
  </code></pre>
  
  <p>When I try to unmarshal the file :</p>
  
  <pre><code>JAXBContext jc = JAXBContext.newInstance("path.to.package.of.schema.objects");
  Unmarshaller u = jc.createUnmarshaller();
  
  // read the file stream and unmarshall the XML
  File f = new File(xmlFilePath);
  Document document = (Document)u.unmarshal(f);
  </code></pre>
  
  <p>am getting the following exception:</p>
  
  <blockquote>
    <p>Exception [EclipseLink-25008] (Eclipse Persistence Services -
    2.1.3.v20110304-r9073): org.eclipse.persistence.exceptions.XMLMarshalException Exception
    Description: A descriptor with default root element
    {urn:kad:ns:file:1}Document was not found in the project</p>
  </blockquote>
  
  <p>Is this something specific for having a urn as the target namespace in the XSD or am I missing something in the JAVA file unmarshalling the XML file?</p>
  
  <p><strong>Edit</strong></p>
  
  <p>When I remove the default namespace declaration form the xml file <code>xmlns="urn:kad:ns:file:1"</code>, the unmarshal process works fine. But no validation occurs, meaning if I remove a required element from the XML, the process will continue at JAVA level and consider this element mapped object as null.</p>
  
  <p>I was wondering what affect does this (the default namespace attribute in root element) have on the unmarshalling process? Does it instantly validate the XML against the XSD at the URN am specifying (which I suspect it is not finding in my case) ?</p>
  
  <p>How can I validate the XML when unmarshalling agaisnt the XSD I have?</p>