How to use TreeTable

Hi,

I'm trying to use the TreeTable for my own data. What I have so far is a table looking like this (sorry, struggling to upload screenshot):

I am first name | I am first value
I am second name | I am second value

Using this code:

static ColumnInfo name = new ColumnInfo("Name") {
        @Nullable
        @Override
        public Object valueOf(Object o) {
            if (o instanceof CustomNode) {
                return ((CustomNode) o).getName();
            }
            else return o;
        }
    };

    static ColumnInfo value = new ColumnInfo("Value") {
        @Nullable
        @Override
        public Object valueOf(Object o) {
            if (o instanceof CustomNode) {
                return ((CustomNode) o).getValue();
            }
            else return o;
        }
    };

    static ColumnInfo[] columns = {name, value};

    public static void main(String[] args) {
        DefaultMutableTreeNode root = new DefaultMutableTreeNode();
        DefaultMutableTreeNode first = new CustomNode("I am first name", "I am first value");
        DefaultMutableTreeNode child = new CustomNode("I am child name", "I am child value");
        DefaultMutableTreeNode second = new CustomNode("I am second name", "I am second value");

        root.add(first);
        second.add(child);
        root.add(second);

        ListTreeTableModel model = new ListTreeTableModel(root, columns);
        TreeTable treeTable = new TreeTable(model) {
            @Override
            public TreeTableCellRenderer createTableRenderer(TreeTableModel treeTableModel) {
                TreeTableCellRenderer tableRenderer = super.createTableRenderer(treeTableModel);
                UIUtil.setLineStyleAngled(tableRenderer);
                tableRenderer.setRootVisible(false);
                tableRenderer.setShowsRootHandles(true);

                return tableRenderer;
            }

            @Override
            public TableCellRenderer getCellRenderer(int row, int column) {
                TreePath treePath = getTree().getPathForRow(row);
                if (treePath == null) return super.getCellRenderer(row, column);

                Object node = treePath.getLastPathComponent();

                @SuppressWarnings("unchecked")
                TableCellRenderer renderer = columns[column].getRenderer(node);
                return renderer == null ? super.getCellRenderer(row, column) : renderer;
            }

            @Override
            public TableCellEditor getCellEditor(int row, int column) {
                TreePath treePath = getTree().getPathForRow(row);
                if (treePath == null) return super.getCellEditor(row, column);

                Object node = treePath.getLastPathComponent();
                @SuppressWarnings("unchecked")
                TableCellEditor editor = columns[column].getEditor(node);
                return editor == null ? super.getCellEditor(row, column) : editor;
            }
        };

        JTree tree = treeTable.getTree();

        tree.setShowsRootHandles(true);

        JFrame frame = new JFrame();
        frame.setBounds(400, 400, 400, 500);
        frame.getContentPane().add(treeTable);
        frame.setVisible(true);
    }

    private static class CustomNode extends DefaultMutableTreeNode {
        String name;
        Object value;

        CustomNode(String name, Object value) {
            this.name = name;
            this.value = value;
        }

        public Object getValue() {
            return value;
        }

        public String getName() { return name; }
    }

However, my end goal is to have collapsible rows in the table. Currently I'm trying to do so by adding a child node to a non root node, but this doesn't achieve what I want. Please may someone point me in the right direction of how I could get collapsible rows.