private function loadCategoriesFromClassContentDirectories($directories)
    {
        $classcontents = [];
        foreach ($directories as $directory) {
            $classcontents = array_merge($classcontents, self::getClassContentClassnamesFromDir($directory));
        }

        foreach ($classcontents as $class) {
            try {
                if (class_exists($class)) {
                    $this->buildCategoryFromClassContent(new $class());
                }
            } catch (ClassNotFoundException $e) {
                // nothing to do
            }
        }
    }