public static function loadSubdivisionUpdateMap()
    {
        if (empty(static::$subdivisionUpdateMap)) {
            $path = __DIR__ . '/../resources/';
            $rawMap = file_get_contents($path . 'subdivision_update_map.json');
            static::$subdivisionUpdateMap = json_decode($rawMap, true);
        }

        return static::$subdivisionUpdateMap;
    }