Use the standard entity handler pattern

Thanks @jonathanshaw, good catch and what you have looks right to me. There are many instances of "getHandler('registration', 'host_entity')" in the module beyond wait list - I am thinking we should correct those to use the new pattern "getHandler($entity->getEntityTypeId(), 'registration_host_entity');" rather than using the deprecated example.

I wonder if there's also value in adding a static helper to HostEntity:

public static function create(Entity interface $entity) {
 $handler = \Drupal::entityTypeManager()->getHander($entity->getEntityTypeId(), 'registration_host_entity');
  return $hander->createHostEntity($entity);
}

Added a commit and tests are now passing. I will try to add a new test this week that proves that the old method triggers a deprecation warning and the new method doesn't. Then I can merge it.

I am having a lot of trouble getting the deprecation test to work on both D10 and D11.

I finally got the deprecation tests working.

This is really close. Left a couple of comments which may result in code changes. Once those comments are addressed we're good. Thanks for adding the deprecation tests.

Answered on the MR, the code is all good AFAICS.

Ah, makes sense, and I do now recall you mentioning this earlier. Will merge shortly.

Automatically closed - issue fixed for 2 weeks with no activity.