Determine why google_sign_in_android can't use Guava 33.3.0 #154586
Description
Sort of a lazy title.
In #154489, it was determined that an upgrade to Guava in google_sign_in_android caused apps using the plugin to fail to build, with R8 errors:
ERROR: Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in ...\build\app\outputs\mapping\release\missing_rules.txt.
ERROR: R8: Missing class com.google.j2objc.annotations.ReflectionSupport$Level (referenced from: com.google.common.util.concurrent.AbstractFuture)
Missing class com.google.j2objc.annotations.ReflectionSupport (referenced from: com.google.common.util.concurrent.AbstractFuture)
Missing class com.google.j2objc.annotations.RetainedWith (referenced from: com.google.common.collect.ImmutableSet com.google.common.collect.ImmutableMap.entrySet and 3 other contexts)
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:minifyReleaseWithR8'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.R8Task$R8Runnable
> Compilation failed to complete
The upgrade was reverted, to unblock the framework->packages roller, and to unblock use of the package.
We should figure out why this is, and unblock re-landing the upgrade.