In my previous post, I documented the first of my Adventures in Porting a D7 Form Module to Drupal 8. In that article, I documented how I used the Drupal Module Upgrader to convert my Drupal 7 module, Form Fun, to Drupal 8 and what I learned along the way about how Routes and Controllers replaced hook_menu, and what I gleaned from change records about other API changes. This article is a continuation of that post, so you might want to pop over and give it a read so that you're up to speed with what we're doing here.