Topic: Oil cooler sandwich plate, extra hole

[Nicklopic]

Hey, I have a TTR400 oil cooler sandwich plate I’m intending to use on my bike. I’m curious/confused why there seems to be a whole to bleed off/bypass the cooler in the the sandwich plate. I doubt it, but is it something I should plug up before using?
Attached is photos

[Don R]

 Air vent?

[Nicklopic]

Found TTR400 a site and email, asked him directly
It’s a bypass incase the cooler gets plugged up you don’t loose oil pressure completely. Just seemed weird it would be just a hole instead of like an actual check valve

[Bodi]

It makes sense, but the cooler won't get full oil flow... doubt that it needs it though. A check valve? Flow can only be one way so why? Oil comes into the bottom of the plate instead of directly into the filter cover, without the hole it would go through the cooler and back into filter case then the filtered oil into the "bolt". The hole bypasses the cooler in case it somehow (?) gets plugged, but the cooler will still get oil flow and do what cooling it can.
Mine does not have any bypass hole but I haven't had any oil pressure problems as far as I can tell. Maybe it's in case a cooler hose gets kinked?