code: protected void addNavigationBarHeader(Content body) {
          Content headerContent;
          if (configuration.packagesheader.length() > 0) {
              headerContent = new RawHtml(replaceDocRootDir(configuration.packagesheader));
          } else {
              headerContent = new RawHtml(replaceDocRootDir(configuration.header));
          }
          Content heading = HtmlTree.HEADING(HtmlConstants.TITLE_HEADING, true,
                  HtmlStyle.bar, headerContent);
          body.addContent(heading);
      }
docs: {@inheritDoc}