We can't use GitHub authentication during the initial provisioning of the environment. The Windows slave needs to be able to connect using basic authentication, and it also seems that you can't actually login for the first time if GitHub is configured as the authentication source.
Since CASC is reapplied every time Jenkins restarts, we will need some kind of additional configuration file that has the GitHub configuration. For any subsequent restarts, we need this file applied rather than the original file that configures basic authentication.
We can't use GitHub authentication during the initial provisioning of the environment. The Windows slave needs to be able to connect using basic authentication, and it also seems that you can't actually login for the first time if GitHub is configured as the authentication source.
Since CASC is reapplied every time Jenkins restarts, we will need some kind of additional configuration file that has the GitHub configuration. For any subsequent restarts, we need this file applied rather than the original file that configures basic authentication.