public static function get_declared_target_and_indicators_instances(array $definition): array {

        $target = static::get_target($definition['target']);

        $indicators = [];

        foreach ($definition['indicators'] as $indicatorname) {
            $indicator = static::get_indicator($indicatorname);
            $indicators[$indicator->get_id()] = $indicator;
        }

        return [$target, $indicators];
    }