code: public static void generate(ConfigurationImpl configuration,
                                  ClassTree classtree) {
          TreeWriter treegen;
          DocPath filename = DocPaths.OVERVIEW_TREE;
          try {
              treegen = new TreeWriter(configuration, filename, classtree);
              treegen.generateTreeFile();
              treegen.close();
          } catch (IOException exc) {
              configuration.standardmessage.error(
                          "doclet.exception_encountered",
                          exc.toString(), filename);
              throw new DocletAbortException(exc);
          }
      }
docs: Create a TreeWriter object and use it to generate the
  "overview-tree.html" file.
  
  @param classtree the class tree being documented.
  @throws  DocletAbortException