code: protected void generatePackageUseFile() throws DocFileIOException {
          HtmlTree body = getPackageUseHeader();
          HtmlTree div = new HtmlTree(HtmlTag.DIV);
          div.addStyle(HtmlStyle.contentContainer);
          if (usingPackageToUsedClasses.isEmpty()) {
              div.addContent(contents.getContent("doclet.ClassUse_No.usage.of.0", utils.getPackageName(packageElement)));
          } else {
              addPackageUse(div);
          }
          if (configuration.allowTag(HtmlTag.MAIN)) {
              mainTree.addContent(div);
              body.addContent(mainTree);
          } else {
              body.addContent(div);
          }
          HtmlTree tree = (configuration.allowTag(HtmlTag.FOOTER))
                  ? HtmlTree.FOOTER()
                  : body;
          addNavLinks(false, tree);
          addBottom(tree);
          if (configuration.allowTag(HtmlTag.FOOTER)) {
              body.addContent(tree);
          }
          printHtmlDocument(null, true, body);
      }
docs: Generate the package use list.
  @throws DocFileIOException if there is a problem generating the package use page