As explained in https://doc.ez.no/display/PR/PlatformUI+-+content+view+-+sub-items+widget

The subitems should be viewable in different forms and this should be extensible. Each "form" is represented by an icon which also serves as a way to enable or disable a form.

The results of this story should be:

1. the ability to fold/unfold the subitems by using the list view icon or the arrow near "sub-items"
2. a dedicated View representing the list view