Context: This is the email I sent google, listing issues I came across when working with their carddav server. More information in this blogpost. I reformatted and redacted the email to protect people's privacy.
Hello redacted,
You may have figured it from the other emails, but we are currently working on providing a syncronization tool with Google's new CardDAV server. We've run into a number of issues that are definitely bugs, and looking for some advise in a different area.
I would much appreciate it if you could take a look at these, but I'd also completely understand if you're busy. Regardless, I feel that this information may be helpful for you, because I feel I will not the last to mention them