[Closed] how to connect two Di2 cables?

okay, I'm converting a mate's bike from drops to flat bars.

It currently runs a 1x11 with roadie Di2 shifters and a XT rear mech, so the left shifter is functionally redundant (no front mech) but is part of the wiring.

Now... I want to do the conversion with minimum fuss (if possible). To go flat bar I have the XT shifter but the current wiring goes in and out of the left roadie shifter. I need to connect these two wires together to bypass the LH shifter.

What item do I need to connect two Di2 cables together? Basically a female-to-female connector.

So far my searching has drawn a blank (albeit 7 minutes...). I could just get a longer cable but then I'd have to dig inside the frame etc. which I'd rather not do. If I can connect the two wires I should be okay.

This seems to look possible, although it's 2-in-2-out..?
https://www.chainreactioncycles.com/shimano-e-tube-di2-junction-box/rp-prod85153