Since #18445, the plugin and related classes may be reloaded, losing registrations - probably for plugin registrations, default dashboard widgets, modified menu items, and permissions.

The change to use require_dependency will allow Rails to track the constants and reload them when the source files are modified, discarding the class variable. The use of require_dependency is however required to ensure eager loading doesn't load the file twice (#18445).

The source files may need to be moved to prevent double-loading and to be excluded from autoloading.