Filter Hook: Filter to check if the RSVP has meta.
Function: Whether the passed ticket provider class string (or its slug) is active.
Filter Hook: Allow filtering the relationships so providers can add their own strings.
Method: Get the Provider class name from its slug.
Method: Determine whether we should enqueue the ARI assets.
Method: Return the string representation of this provider class as the class name for backwards compatibility.
Method: Given a post ID, get the instance of the saved or default ticket provider class.
Method: Given a provider string (class module name or slug), get its class instance if an active module.
Method: Given a ticket provider, get its Attendee Optout Meta Key from its class property (or constant if legacy).
Method: Whether a post has tickets from this provider, even if this provider is not the default provider.