Migrate field_collections I'm using Drush and the migrate tools to migrate a Drupal 7 site to Drupal 8. The site uses field_collections which do not migrate. The field_collections page indicates it is probably being deprecated and recommends moving to paragraphs.

I have searched, but all of the custom migrations I have found so far have been flat fielded. I need to figure out a way to convert field_collections to paragraphs, or field_collections to custom entities.

I am generally comfortable with PHP and OOP, but building the entities and/or migrations in a new module have me confused.

How would I proceed to build a migration for a content type that included one or more field_collections, so that the field_collection data would be available in Drupal 8?
There's a patch in development for the Paragraphs module to support migration in Drupal 8. This work is currently undergoing development with recent activity. This might be a good way to get a start on your own work and contribute back to the community.