code: public static void generate(ConfigurationImpl configuration,
                                  ClassTree classtree) throws DocFileIOException {
          DocPath filename = DocPaths.OVERVIEW_TREE;
          TreeWriter treegen = new TreeWriter(configuration, filename, classtree);
          treegen.generateTreeFile();
      }
docs: Create a TreeWriter object and use it to generate the
  "overview-tree.html" file.
  
  @param configuration the configuration for this doclet
  @param classtree the class tree being documented.
  @throws  DocFileIOException if there is a problem generating the overview tree page