Bumps target SDK version of grpc-android, grpc-cronet, grpc-android-interop-testing to API 29. Major related changes are:
- Migrated android.support to androidx, which is required for Android Q.
- android.net.NetworkInfo is deprecated in SDK 29, suppressed compiler warnings as it is needed for supporting old Android versions.
- Robolectric requires Java 9+ for Android 29, which causes unit tests in grpc-cronet fail. Added annotation to emulate Android 28 for grpc-cronet's test.
- Upgraded Android dependencies accordingly in android-interop-testing.
On Android, there is a race between making new RPCs and reconnecting after network comes back. If the former happens first, RPCs fail immediately. This is because resetConnectBackoff() does not update the picker before trying to reconnect and new RPCs are sent with the old picker, which fails RPCs immediately.
In this change, we move to use enterIdle(), which updates the channel picker to cause new RPCs being buffered (while subchannels are in reconnecting), at the moment network recovers. Hopefully, this can avoid RPCs being dropped prematurely in network recovery.
For Android version 28, some constants in ConnectivityManager have been deprecated such as ConnectivityManager. CONNECTIVITY_ACTION, ConnectivityManager. TYPE_WIFI, ConnectivityManager. TYPE_MOBILE, etc. In grpc-android, they are used for supporting legacy SDK connectivity state monitoring (and its unit tests). They work as intended for legacy SDK versions. So we suppress those warnings for the target SDK version 28.
Add grpc-android into main build. grpc-android will be built if Gradle option skipAndroid is false. This change also migrates deprecated Robolectric methods to androidx.test methods.
* Added missing Javadoc for public methods, deprecate fromBuilder and replace with usingBuilder.
* Removed unnecessary final keyword for static methods.
* call usingBuilder in deprecated fromBuilder
* Changed Javadoc description for usingBuilder method.
ZHANG Dapeng