shadows/framework/src/main/java/org/robolectric/shadows/ShadowAudioManager.java
@Implementation(minSdk = O)
  protected int requestAudioFocus(android.media.AudioFocusRequest audioFocusRequest) {
    lastAudioFocusRequest = new AudioFocusRequest(audioFocusRequest);
    return nextResponseValue;
  }
@Implementation(minSdk = O)
  protected int requestAudioFocus(android.media.AudioFocusRequest audioFocusRequest) {
    lastAudioFocusRequest = new AudioFocusRequest(audioFocusRequest);
    return nextResponseValue;
  }
Provides a mock like interface for the requestAudioFocus method by storing the request object
for later inspection and returning the value specified in setNextFocusRequestResponse.