ConcatenatingMediaSource to ConcatenatingMediaSource2

I have a list of files and for each of those file I create MediaSource like

                MediaSource mediaSource = new ProgressiveMediaSource.Factory(dataSourceFactory)
                        .createMediaSource(
                                MediaItem.fromUri(
                                Uri.fromFile(new File("path_to_file")))
                                        .buildUpon()
                                        .setMediaMetadata(mediaMetadata)
                                        .setTag(filesList.getNpPodKolko())
                                        .build()
                        );

and then I add this to

concatenatingMediaSource.addMediaSource(mediaSource);

where concatenatingMediaSource is defines as follows:
ConcatenatingMediaSource concatenatingMediaSource = new ConcatenatingMediaSource();

I want to migrate this to ConcatenatingMediaSource but I get the error:
Progressive media source must define an initial placeholder duration

How can I calculate the desired placeholder duration ?