Strange Yellow Bung R8170

[Rupie]

Morning, Trying to install a pair of R8170 Di2 Shifters and all is Ok but within the back of the unit, where the clamp onto the bar there is a yellow bung. If I press it oil squirts out the correct opening where the hydraulic cable will be fitted. What I need to know is do I need to leave it in place. I do not want to tighten everything and it fractuer part of the casing. Nor do I want to leave it out then have to disassemble everything to put it in.
The Shimano instructions and most of th Youtube videos I have watched to not mention its existence. Even component exploded views ?
Thanks
Rupert

 

[Colin S]

I think it will be a plug in the brake hose entry port. You will need to remove this to fit the hose.

Colin