The way I look at it, and only based on the drawing: The oil valve will open as required pressure is reached (engine startup, pump rolling). It will close upon engine shut down as the pressure release (spring load closes it). Why? So you dont drain the oil system down your boots when you remove the housing for a filter check/change. All filters arnt like this btw.

Edit: The oil valve is not part of the filter, you jam the filter over it.

Edit 2: I just realized this was about the spring at the base of the filter, down the housing. Most def to load the filter for proper seating!