public static function create_conversation_between_users(array $userids) {
        debugging('\core_message\api::create_conversation_between_users is deprecated, please use ' .
            '\core_message\api::create_conversation instead.', DEBUG_DEVELOPER);

        // This method was always used for individual conversations.
        $conversation = self::create_conversation(self::MESSAGE_CONVERSATION_TYPE_INDIVIDUAL, $userids);

        return $conversation->id;
    }