How to define TargetSDK in TestRunner of Robolectric 3.0

When using Robolectric 2.4, we could define our testRunner to obtained our AndroidManifest, and defined our getTargetSdkVersion as code below.

@Override
protected AndroidManifest getAppManifest(Config config) {
    return new AndroidManifest(Fs.fileFromPath(MANIFEST_PROPERTY), Fs
            .fileFromPath(RES_PROPERTY)) {

        @Override
        public int getTargetSdkVersion() {
            return TARGET_SDK_VERSION;
        }
    };
}

In Robolectric 3.0, this has been changed where we define getting AndroidManifest as below

@Override
protected AndroidManifest getAppManifest(Config config) {
    return createAppManifest(Fs.fileFromPath(MANIFEST_PROPERTY), Fs.fileFromPath(RES_PROPERTY), Fs.fileFromPath(ASSET_PROPERTY));

}

This is good. But now, how could I set the getTargetSdkVersion in Robolectric 3.0 now? Note in Android Studio, we don't define the TargetSdkVersion in AndroidManifest. I currently use @Config to workaround it, but would like to put everything in the TestRunner class.