creating a tree-like jtable with column span

[Phaelax]

I need to create table with expandable rows. Each row in the table can be expanded to display a secondary row. While I have managed this in the past for other projects, this problem is slightly unique. For the rows that are always visible, I want them to be only 1 column yet stretch across multiple columns. (in HTML, think of the 'colspan' attribute)

I've drawn the interface I'm trying to achieve which should help explain the result I'm after.
interface design

Any thoughts on how I could go about achieving this?

[Ezzaral]

Have you tried using a JTreeTable?

[Phaelax]

The parent nodes still require the same number of columns as the children. In that jtreeTable example, I would still need to span the folder row across all 4 columns.