[Question] Which properties to save/restore on rotation?

I could not find any information about that in the examples. I have seen basically the same question here, but there was no explanations but links to commits.

For example, I save/restore cameraPosition in order to keep the view state of a Google Map on rotation. I want to do a similar thing for PhotoView, but I am not sure what/how. I have tried to save/restore scale but it did not work. I am NOT asking about the general mechanism for saving/restoring values on rotation on the Android platform; I already know that. I am asking about the properties of PhotoView, and the way to set those values to back to the newly created PhotoView.

In short, I want to keep the view state of PhotoView on screen rotation.