Configuring webhooks to communicate with self-signed certificate endpoints in k8s

I’m relatively new to gitlab and was trying to play with it on IBM cloud private following install instructions at https://medium.com/@zhimin.wen/gitlab-on-onprem-kubernetes-icp-3-1-b06dcd09df7c

This gave me a gitlab running in k8s with self-signed certificates … so far so good. I then created a project and tried to configure a webhook to talk to a jenkins I have running in k8s but I get ssl certificate problems. I think this is because the Jenkins is also running with a self signed certificate and the gitlab instance cannot verify it.

Try as I might I cannot find a cohesive set of instructions for adding the Jenkins certificate into gitlab … anyone got any pointers?