code: public Content getClassHeader(TypeElement typeElement) {
          Content classLink = (isVisibleClass(typeElement))
                  ? getLink(new LinkInfoImpl(configuration, LinkInfoImpl.Kind.DEFAULT, typeElement)
                          .label(configuration.getClassName(typeElement)))
                  : new StringContent(utils.getFullyQualifiedName(typeElement));
          Content li = HtmlTree.LI(HtmlStyle.blockList, getMarkerAnchor(
                  utils.getFullyQualifiedName(typeElement)));
          Content superClassLink = typeElement.getSuperclass() != null
                  ? getLink(new LinkInfoImpl(configuration, LinkInfoImpl.Kind.SERIALIZED_FORM,
                          typeElement.getSuperclass()))
                  : null;
  
          //Print the heading.
          Content className = superClassLink == null ?
              configuration.getContent(
              "doclet.Class_0_implements_serializable", classLink) :
              configuration.getContent(
              "doclet.Class_0_extends_implements_serializable", classLink,
              superClassLink);
          li.addContent(HtmlTree.HEADING(HtmlConstants.SERIALIZED_MEMBER_HEADING,
                  className));
          return li;
      }
docs: Get the serializable class heading.
  
  @param typeElement the class being processed
  @return a content tree for the class header