code: private void buildTree(ClassDoc[] classes) {
          for (ClassDoc aClass : classes) {
              // In the tree page (e.g overview-tree.html) do not include
              // information of classes which are deprecated or are a part of a
              // deprecated package.
              if (configuration.nodeprecated &&
                      (utils.isDeprecated(aClass) ||
                      utils.isDeprecated(aClass.containingPackage()))) {
                  continue;
              }
  
              if (configuration.javafx
                      && aClass.tags("treatAsPrivate").length > 0) {
                  continue;
              }
  
              if (aClass.isEnum()) {
                  processType(aClass, configuration, baseEnums, subEnums);
              } else if (aClass.isClass()) {
                  processType(aClass, configuration, baseclasses, subclasses);
              } else if (aClass.isInterface()) {
                  processInterface(aClass);
              } else if (aClass.isAnnotationType()) {
                  processType(aClass, configuration, baseAnnotationTypes,
                      subAnnotationTypes);
              }
          }
      }
docs: Generate mapping for the sub-classes for every class in this run.
  Return the sub-class list for java.lang.Object which will be having
  sub-class listing for itself and also for each sub-class itself will
  have their own sub-class lists.
  
  @param classes all the classes in this run.
  @param configuration the current configuration of the doclet.