[google_sign_in_android] Corrects typo in logs

[Milvintsiss]

Corrects minor typo in logs printed by plugin.

Pre-launch Checklist

• [x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [x] I read the Tree Hygiene wiki page, which explains my responsibilities.
• [x] I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/plugins repo does use dart format.)
• [x] I signed the CLA.
• [x] The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• [x] I listed at least one issue that this PR fixes in the description above.
• [x] I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• [x] I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style.
• [ ] I updated/added relevant documentation (doc comments with ///).
• [x] I added new tests to check the change I am making, or this PR is test-exempt.
• [x] All existing and new tests are passing.

[flutter-dashboard[bot]]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat (don't just cc him here, he won't see it! He's on Discord!).

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

[Hixie]

We could test this.

More importantly, shouldn't we not be printing those logs anyway? https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#only-log-actionable-messages-to-the-console It could be made more helpful (e.g. explaining what line of code is wrong somehow), which would make it more actionable, in which case it might be more helpful.

[Milvintsiss]

We could test this.

More importantly, shouldn't we not be printing those logs anyway? https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#only-log-actionable-messages-to-the-console It could be made more helpful (e.g. explaining what line of code is wrong somehow), which would make it more actionable, in which case it might be more helpful.

We should keep the first one because many users probably still use clientId field to provide serverClientId (it was the old behavior before 6.0.0) and this warning is fixable. The other should be documented in the readme of google_sign_in and not be a warning. Usage of both clientId and serverClientId is the correct way for an iOS app and will not break anything for Android, it's just not needed/used for Android.

[Hixie]

test-exempt: based on discussions on discord, the cost of testing this outweighs the value of avoiding regressions in this code.

[stuartmorgan]

@camsim99 this should be ready for your final approval.