SWING's JToolbar separator orientation

Question

I found a task which says that:

SWING does not contain component which implements separator (vertical or horizontal) depending on toolbar orientation. By inheriting JComponent, make component which has that implementation, and take into assumption that its parent should always be JToolbar component.

Would someone mind explaining to me how separator does not depend on toolbar orientation? I thought that by specifying in JToolbar constructor how should orientation be made, I already do that. (I'm using addSeparator() method from JToolbar class, not JSeparator)