code: @Implementation
    protected static int nativeAddTrack(
        long nativeObject, @NonNull String[] keys, @NonNull Object[] values) {
      AtomicInteger nextTrackIndex = nextTrackIndices.get(nativeObject);
      if (nextTrackIndex == null) {
        throw new IllegalStateException("No next track index configured for key: " + nativeObject);
      }
  
      return nextTrackIndex.getAndIncrement();
    }
docs: Returns an incremented track id for the associated muxer.