The doors don't belong to rooms, the floor plan is a list of FloorMapItem that can be a room/door/window/opening/outside, so we can't tell between which rooms a door is.
The way I would approach it:
Each room is a set of Vector3 points.
Each door is also a Vector3 point located on the room edges.
So you can check if the door belongs to a room with this kind of method from ControlPointsController.cs
protected bool IsInsidePoints(Vector3 doorWorldPosition)
List<Vector2> poly = MathUtils.ConvertVector3To2(GetPointsWorldPositionList(), MathUtils.PlanType.XZ);
Vector2 point = MathUtils.ConvertVector3To2(doorWorldPosition, MathUtils.PlanType.XZ);
bool isDoorInRoom= MathUtils.IsInPolygon(point, poly);
//Debug.Log("isDoorInRoom:" + isDoorInRoom);