Fix malformed Schema Reference during field_behavior generation

[gganley]

References to other Issues or PRs

Fixes #1937

Have you read the Contributing Guidelines?

To the best of my ability.

Brief description of what is fixed or changed

The required field was being added to a schema reference, this no longer does so.

Other comments

Added two googleapi proto files to help conform to google AIP examples.

[google-cla]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[gganley]

@googlebot I signed it!

[gganley]

Quick scan looks like this test relies on stable order from ranging over a map.

[johanbrandhorst]

Thanks a lot for this PR @gganley! I left a note about adding a comment to explain the behaviour, and I'm generally confused as to why we need the new proto dependencies.

[johanbrandhorst]

Hi, please rebase on master to get the fix for the flaky test.

[gganley]

@johanbrandhorst apologies if it's not the proper etiquette to re-request reviews rather than resolving the conversations myself.

[johanbrandhorst]

Thanks a lot for this fix 😄.