protected function get_data_to_serialize() {
		return array(
			'recipient'    => $this->recipient->ID,
			'message'      => $this->message,
			'subject'      => $this->subject,
			'strategy'     => $this->strategy,
			'manager'      => $this->manager->get_type(),
			'data_sources' => $this->data_sources
		);
	}