Just a few generic pointers. There is a scheme that is used in several places, leveraging Symphony, and its used for Record Mappers.
It’s a way of building a “registry” of classes to call, just based on the fact that they implement an interface.
You can start tracking it from config/core_services.yaml, some services get tagged, and the registry class is called with a list of those tagged services.
If you have a class that implements one of the RecordMapper interfaces, the Symphony cache:clear should pick it up, and you can check it like this:
symfony console debug:container ViewDefinitionMapperInterface
Some of the Docs and videos use similar mechanisms.
Once it is loaded into the registry, normally some place in the code will iterate and call all defined mappers when it is appropriate.