public function get_ticket_global_id( $ticket_id, $provider_class = null ) {
		$existing = get_post_meta( $ticket_id, $this->global_id_key, true );

		if ( ! empty( $existing ) ) {
			return $existing;
		}

		if ( null === $provider_class ) {
			/** @var Tribe__Tickets__Tickets $provider */
			$provider = tribe_tickets_get_ticket_provider( $ticket_id );

			if ( ! $provider instanceof Tribe__Tickets__Tickets ) {
				return false;
			}

			$provider_class = get_class( $provider );
		}

		$generator = new Tribe__Tickets__Global_ID();
		$generator->origin( home_url() );
		$type = $this->get_provider_slug( $provider_class );
		$generator->type( $type );

		$global_id = $generator->generate( array(
			'type' => $type,
			'id'   => $ticket_id,
		) );

		update_post_meta( $ticket_id, $this->global_id_key, $global_id );

		return $global_id;
	}