You're creating apps (CI, review apps) via the Builds API but you're not sure what does use as the value of the
If you are using a public GitHub repo for your source code, GitHub provides a specific URL for each repo that resolves to a tarball of the repo’s contents. This URL typically looks like:
If the repository is private you may need to append an access token:
https://api.github.com/repos/<username>/<repo name>/tarball/master/?access_token=<github access token>
See this article for a step-by-step walkthrough of setting up apps using the Platform API.