code: private void initTopicTree(HelpTopicNode htnParent, TreeNode ttnParent) {
          
          for (int i = 0; i < ttnParent.getChildCount(); i++) {
              TreeNode ttnChild = ttnParent.getChildAt(i);
              HelpTopic ht = getTopic(ttnChild);
              HelpTopicNode htnChild = new HelpTopicNode(ht);
              htnParent.addChild(htnChild);
              initTopicTree(htnChild, ttnChild);
          }
          
      }
docs: Duplicates JavaHelp topic tree into HelpTopicNode-based tree.
  
  @param htnParent Current parent for HelpTopicNode-based tree.
  @param ttnParent Current parent for JavaHelp TreeNode-based tree.