Our master git repo is https://code.googlesource.com/google-api-go-client
We do NOT use Github pull requests. We use Gerrit instead with the same workflow as Go. See https://golang.org/doc/contribute.html
Most of this project is auto-generated.
The notable directories which are not auto-generated:
google-api-go-generator/ -- the generator itself
googleapi/ -- shared common code, used by auto-generated code
examples/ -- sample code