that is labelled as a warning, not an error-- are there any other errors in the logs?
Also, can you confirm that you have the GCM.jar file from google-support on your build path? That needs to be bundled up in the apk, which your IDE should do automatically. Are you using Android Studio or Eclipse?
about 6 years ago
Sorry for this long delay. Yes this is a warning, but I have this error message :
Error:Execution failed for task ':app:proguardFreeRelease'.
> java.io.IOException: Please correct the above warnings first.
In debug mode everything is fine, but as soons as I build the app in release mode, I have hundreds of warnings like the previous one. So I had the gcm.jar in my libs folder (I'm using android studio) but now I have this warning :
`Warning:com.google.api.client.repackaged.com.google.common.base.Joiner: can't find referenced class javax.annotation.Nullable`