My ViewModel class implements LifecycleObserver. When I call fragment.lifecycle.addObserver(this) it produces exception.

Caused by: java.lang.IllegalArgumentException: The observer class has some methods that use newer APIs which are not available in the current OS version. Lifecycles cannot access even other methods so you should make sure that your observer classes only access framework classes that are available in your min API level OR use lifecycle:compiler annotation processor.

Strange, that firstly it was working fine, but not long ago this exception has appeared. I've found, that audioFocusRequest is cause of this bug.

private val audioFocusRequest by lazy {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN)
        .setOnAudioFocusChangeListener(this)
        .build() else throw RuntimeException("Can't be done for Android API lower than 26")
}

Does anybody know how it can be fixed?

UPD

Tried to use annotationProcessor "androidx.lifecycle:lifecycle-compiler:$lifecycle_version", but got compilation error: (decided to paste screenshot, because whole logs are quite big)

UPD 2
At the end I've decided to delete audioFocusRequest field and to use old deprecated method - requestAudioFocus(OnAudioFocusChangeListener l, int streamType, int durationHint) instead of recommended requestAudioFocus(@NonNull AudioFocusRequest focusRequest)

It helped me to make code working again, so it can be solution. But I didn't find answer - why this problem had appeared. It strange because code used to be working before.

So problem has been solved but question still stays unanswered