code: protected void generatePackageUseFile() throws IOException {
          Content body = getPackageUseHeader();
          HtmlTree div = new HtmlTree(HtmlTag.DIV);
          div.addStyle(HtmlStyle.contentContainer);
          if (usingPackageToUsedClasses.isEmpty()) {
              div.addContent(getResource(
                      "doclet.ClassUse_No.usage.of.0", pkgdoc.name()));
          } else {
              addPackageUse(div);
          }
          body.addContent(div);
          addNavLinks(false, body);
          addBottom(body);
          printHtmlDocument(null, true, body);
      }
docs: Generate the package use list.