protected function _routerPrefixes()
    {
        $cache = static::cache('_routerPrefixes');
        if (!$cache) {
            $prefixes = [];
            foreach (Router::routes() as $route) {
                if (empty($route->defaults['prefix'])) {
                    continue;
                } else {
                    $prefix = Inflector::camelize($route->defaults['prefix']);
                    if (!in_array($prefix, $prefixes)) {
                        $prefixes[] = $prefix;
                    }
                }
            }

            $cache = static::cache('_routerPrefixes', $prefixes);
        }

        return $cache;
    }