So in effect you want to know whether empty spaces on the other side of the door allows a figure to draw a line of sight through the door that does not occupy a space on this side of the door.
In other words: Can you attack a door by targeting a space the door occupies on the other side of the door?
RRG:
1. Line of sight says that a figure does not block line of sight to itself and a target figure does not block line of sight.
2. Attacking Objects does not say anything about a target object not blocking line of sight to itself.
3. Doors say that a figure cannot draw line of sight through a door.
It could be elsewhere, but I did not find a rule that allows you to draw line of sight through a door when attacking the door.
Edited by a1bert