*                                    When not provided (`null`) all the types.
	 * @return void
	 */
	public function send( $force = false, $filter_types = null ) {

		$this->add_subscriptions( $filter_types );

		foreach ( $this->get_subscriptions() as $subscriber => $types ) {
			foreach ( $types as $type ) {

				$this->send_one( $type, $subscriber, $force );

			}
		}

		/**
		 * Cleanup subscriptions so if the notification
		 * is triggered again we don't have incorrect subscribers
		 * on the next trigger.
		 * This happens when receipts are triggered in bulk by action scheduler.
		 */