public static function get_all_indicators() {
        if (self::$allindicators !== null) {
            return self::$allindicators;
        }

        $classes = self::get_analytics_classes('indicator');

        self::$allindicators = [];
        foreach ($classes as $fullclassname => $classpath) {
            $instance = self::get_indicator($fullclassname);
            if ($instance) {
                self::$allindicators[$instance->get_id()] = $instance;
            }
        }

        return self::$allindicators;
    }