Program: 98461
Project: 98461
Buggy source:
public ProductTree(){
  super();
  root=new NodeItem(Product.class);
  model=new DefaultTreeModel(root);
  map=new HashMap<String,NodeItem>();
  setModel(model);
  getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
  setShowsRootHandles(false);
  addTreeSelectionListener(new TreeSelectionListener(){
    /** 
 * The valueChanged listener is called all the time. The most crucial part is that it accurately distinguishes between class and product selection. If it's a class selection, it fires a classSelectionEvent which is either handled as a DB or cache query. A product selection results in a productSelection event firing which ends up filling in the form in the GUI.
 */
    @Override public void valueChanged(    TreeSelectionEvent event){
      if (event.isAddedPath()) {
        if (productEditedListener != null && lastSelectedNode != null && (!lastSelectedNode.getClass().equals(Class.class))) {
          System.out.println("String_Node_Str");
          ActionEvent edited=new ActionEvent((Product)lastSelectedNode.getStoredObject(),0,"String_Node_Str");
          productEditedListener.actionPerformed(edited);
        }
        TreePath path=event.getNewLeadSelectionPath();
        NodeItem selectedNode=(NodeItem)path.getLastPathComponent();
        Object o=selectedNode.getStoredObject();
        if (o.getClass().equals(Class.class)) {
          String s=o.toString();
          ActionEvent i=new ActionEvent(model,0,s);
          classSelectListener.actionPerformed(i);
        }
 else {
          ActionEvent s=new ActionEvent((Product)selectedNode.getStoredObject(),0,"String_Node_Str");
          productSelectedListener.actionPerformed(s);
          lastSelectedNode=selectedNode;
          System.out.println(lastSelectedNode.toString());
        }
      }
    }
  }
);
  addTreeExpansionListener(new TreeExpansionListener(){
    @Override public void treeCollapsed(    TreeExpansionEvent event){
    }
    /** 
 * The treeExpanded method is similar to valueChanged - it fires the same classSelected event but seeing as products can't have children it doesn't need to worry about updating the form. The main purpose in this existing is for when products are added and automatically scrolled to. This doesn't could as a valueChanged event, but a treeExpanded event, and it needs to react accordingly.
 */
    @Override public void treeExpanded(    TreeExpansionEvent event){
      TreePath path=(TreePath)event.getPath();
      if (!(path == null)) {
        NodeItem selectedNode=(NodeItem)path.getLastPathComponent();
        Object o=selectedNode.getStoredObject();
        if (o.getClass().equals(Class.class)) {
          String s=o.toString();
          ActionEvent i=new ActionEvent(model,0,s.substring(s.lastIndexOf(' ') + 1));
          classSelectListener.actionPerformed(i);
        }
      }
    }
  }
);
}

Fixed version (ground truth):
public ProductTree(){
  super();
  root=new NodeItem(Product.class);
  model=new DefaultTreeModel(root);
  map=new HashMap<String,NodeItem>();
  setModel(model);
  getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
  setShowsRootHandles(false);
  addTreeSelectionListener(new TreeSelectionListener(){
    /** 
 * The valueChanged listener is called all the time. The most crucial part is that it accurately distinguishes between class and product selection. If it's a class selection, it fires a classSelectionEvent which is either handled as a DB or cache query. A product selection results in a productSelection event firing which ends up filling in the form in the GUI.
 */
    @Override public void valueChanged(    TreeSelectionEvent event){
      if (event.isAddedPath()) {
        if (productEditedListener != null && lastSelectedNode != null && (!lastSelectedNode.getClass().equals(Class.class))) {
          ActionEvent edited=new ActionEvent((Product)lastSelectedNode.getStoredObject(),0,"String_Node_Str");
          productEditedListener.actionPerformed(edited);
        }
        TreePath path=event.getNewLeadSelectionPath();
        NodeItem selectedNode=(NodeItem)path.getLastPathComponent();
        Object o=selectedNode.getStoredObject();
        if (o.getClass().equals(Class.class)) {
          String s=o.toString();
          ActionEvent i=new ActionEvent(model,0,s);
          classSelectListener.actionPerformed(i);
        }
 else {
          ActionEvent s=new ActionEvent((Product)selectedNode.getStoredObject(),0,"String_Node_Str");
          productSelectedListener.actionPerformed(s);
          lastSelectedNode=selectedNode;
        }
      }
    }
  }
);
  addTreeExpansionListener(new TreeExpansionListener(){
    @Override public void treeCollapsed(    TreeExpansionEvent event){
    }
    /** 
 * The treeExpanded method is similar to valueChanged - it fires the same classSelected event but seeing as products can't have children it doesn't need to worry about updating the form. The main purpose in this existing is for when products are added and automatically scrolled to. This doesn't could as a valueChanged event, but a treeExpanded event, and it needs to react accordingly.
 */
    @Override public void treeExpanded(    TreeExpansionEvent event){
      TreePath path=(TreePath)event.getPath();
      if (!(path == null)) {
        NodeItem selectedNode=getSelectedNode();
        Object o=selectedNode.getStoredObject();
        if (o.getClass().equals(Class.class)) {
          String s=o.toString();
          ActionEvent i=new ActionEvent(model,0,s);
        }
      }
    }
  }
);
}