title: How do I use JAXB @XmlValue in extended class?
body: <p>I have XML like this:</p>
  
  <pre><code>*&lt;link:label xlink:type="resource" 
   xlink:label="label" 
   xlink:role="http://www.xbrl.org/2003/role/label" 
   xlink:title="title" xml:lang="en" id="label_id"&gt;
   Firm's symbol&lt;/link:label&gt;*
  </code></pre>
  
  <p>I have three class in my domain:</p>
  
  <p>1:Label </p>
  
  <pre><code>@XmlRootElement(name = "label",namespace = "http://www.xbrl.org/2003/linkbase")
  
  public class Label extends Resource {
  
  @Column(name = "value")
  private String value;
  
  public Label() {
  }
  
  @XmlValue
  public String getValue() {
      return value;
  }
  </code></pre>
  
  <p>2:Resource </p>
  
  <pre><code>@Inheritance(strategy = InheritanceType.JOINED)
  public abstract class Resource extends ExtendedLinkElement {
  
  
  private String id_resource;
  private String label;
  private String role;
  private String title;
  private String type;
  public Resource() {
  }
  }
  @XmlAttribute( name = "label",namespace = "http://www.w3.org/1999/xlink")
  public String getLabel() {
      return label;
  }
  @XmlAttribute( name = "role",namespace = "http://www.w3.org/1999/xlink")
  public String getRole() {
      return role;
  }
  
  @XmlAttribute( name = "title",namespace = "http://www.w3.org/1999/xlink")
  public String getTitle() {
      return title;
  }
  @XmlAttribute( name = "type",namespace = "http://www.w3.org/1999/xlink")
  public String getType() {
      return type;
  }
  </code></pre>
  
  <p>3:ExtendedLinkElement </p>
  
  <pre><code>@Inheritance(strategy = InheritanceType.JOINED)
  public abstract class ExtendedLinkElement  {
  
  @Id
  @Column(name = "ID")
  private Long id;
  
  public ExtendedLinkElement() {
  
  }
  </code></pre>
  
  <p>But in unmarshal the <code>xml</code> file i get this error:
  <strong>The property or field value can not be annotated with <code>XmlValue</code> since it is a subclass of another XML-bound class</strong></p>
  
  <p>I use moxy for jaxb RI and when i use <code>@xmlMixed</code> , return null in my attribute.</p>