Hi Bhupinder,
You can implement two-level lists(collapsible set as first and list as second) but you should have two-level datasource.
So here is solution:
1 Add Collapsible set on the page.
2 Add List component inside collapsible.
Details: http://prntscr.com/4rls8m/direct
3 Open your service datasource mapping.
4 Create following mapping: http://prntscr.com/4rlt1z/direct
After you will get following result: http://prntscr.com/4rltmm/direct
That's all.
Regards.