code: public Content getClassHeader(ClassDoc classDoc) {
          Content classLink = (classDoc.isPublic() || classDoc.isProtected()) ?
              getLink(new LinkInfoImpl(configuration, LinkInfoImpl.Kind.DEFAULT, classDoc)
              .label(configuration.getClassName(classDoc))) :
              new StringContent(classDoc.qualifiedName());
          Content li = HtmlTree.LI(HtmlStyle.blockList, getMarkerAnchor(
                  classDoc.qualifiedName()));
          Content superClassLink =
              classDoc.superclassType() != null ?
                  getLink(new LinkInfoImpl(configuration,
                          LinkInfoImpl.Kind.SERIALIZED_FORM,
                          classDoc.superclassType())) :
                  null;
  
          //Print the heading.
          Content className = superClassLink == null ?
              configuration.getResource(
              "doclet.Class_0_implements_serializable", classLink) :
              configuration.getResource(
              "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 classDoc the class being processed
  @return a content tree for the class header