code: public Content getHeader(String header) {
          String pkgname = (classDoc.containingPackage() != null)?
              classDoc.containingPackage().name(): "";
          String clname = classDoc.name();
          HtmlTree bodyTree = getBody(true, getWindowTitle(clname));
          HtmlTree htmlTree = (configuration.allowTag(HtmlTag.HEADER))
                  ? HtmlTree.HEADER()
                  : bodyTree;
          addTop(htmlTree);
          addNavLinks(true, htmlTree);
          if (configuration.allowTag(HtmlTag.HEADER)) {
              bodyTree.addContent(htmlTree);
          }
          bodyTree.addContent(HtmlConstants.START_OF_CLASS_DATA);
          HtmlTree div = new HtmlTree(HtmlTag.DIV);
          div.addStyle(HtmlStyle.header);
          if (pkgname.length() > 0) {
              Content classPackageLabel = HtmlTree.SPAN(HtmlStyle.packageLabelInClass, packageLabel);
              Content pkgNameDiv = HtmlTree.DIV(HtmlStyle.subTitle, classPackageLabel);
              pkgNameDiv.addContent(getSpace());
              Content pkgNameContent = getTargetPackageLink(classDoc.containingPackage(),
                      "classFrame", new StringContent(pkgname));
              pkgNameDiv.addContent(pkgNameContent);
              div.addContent(pkgNameDiv);
          }
          LinkInfoImpl linkInfo = new LinkInfoImpl(configuration,
                  LinkInfoImpl.Kind.CLASS_HEADER, classDoc);
          //Let's not link to ourselves in the header.
          linkInfo.linkToSelf = false;
          Content headerContent = new StringContent(header);
          Content heading = HtmlTree.HEADING(HtmlConstants.CLASS_PAGE_HEADING, true,
                  HtmlStyle.title, headerContent);
          heading.addContent(getTypeParameterLinks(linkInfo));
          div.addContent(heading);
          if (configuration.allowTag(HtmlTag.MAIN)) {
              mainTree.addContent(div);
          } else {
              bodyTree.addContent(div);
          }
          return bodyTree;
      }
docs: {@inheritDoc}