"GroupContentEnablerManager" has been renamed to "GroupRelationTypeManager" and works differently

Before:

• $plugin_manager = \Drupal::service('plugin.manager.group_content_enabler');
• Plugin definitions were arrays

After:

• $plugin_manager = \Drupal::service('group_relation_type.manager');
• Plugin definitions are classes of type \Drupal\group\Plugin\Group\Relation\GroupRelationType

This now follows the exact same structure as entity types with one exception: GroupRelationType plugins allow for derivatives whereas EntityType plugins do not (as far as I know).

So:

1. An instance of a plugin is a group relation (versus an entity)
2. The definition of said plugin is a group relation type (versus an entity type)

All related methods for retrieving plugins have been renamed across the code base, no more fooContentPlugin(), but rather:

• $group->getGroupType()->getRelationPlugin($plugin_id)
• $group->getGroupType()->hasRelationPlugin($plugin_id)
• Etc.

Special note about plugin IDs

Because we're allowing derivatives, to get the actual plugin ID, you need to either call getRelationTypeId() on the plugin instance or get the keys from the array returned by the manager when retrieving a list of plugin definitions. If you want the BASE plugin ID, you need to load the actual plugin definition (group relation type) and call id() on that one.