code: protected void addPackageList(Content contentTree) throws IOException {
          Content table = HtmlTree.TABLE(HtmlStyle.useSummary, 0, 3, 0, useTableSummary,
                  getTableCaption(configuration.getResource(
                  "doclet.ClassUse_Packages.that.use.0",
                  getPackageLink(pkgdoc, Util.getPackageName(pkgdoc)))));
          table.addContent(getSummaryTableHeader(packageTableHeader, "col"));
          Content tbody = new HtmlTree(HtmlTag.TBODY);
          Iterator<String> it = usingPackageToUsedClasses.keySet().iterator();
          for (int i = 0; it.hasNext(); i++) {
              PackageDoc pkg = configuration.root.packageNamed(it.next());
              HtmlTree tr = new HtmlTree(HtmlTag.TR);
              if (i % 2 == 0) {
                  tr.addStyle(HtmlStyle.altColor);
              } else {
                  tr.addStyle(HtmlStyle.rowColor);
              }
              addPackageUse(pkg, tr);
              tbody.addContent(tr);
          }
          table.addContent(tbody);
          Content li = HtmlTree.LI(HtmlStyle.blockList, table);
          contentTree.addContent(li);
      }
docs: Add the list of packages that use the given package.
  
  @param contentTree the content tree to which the package list will be added