private function readFile()
    {
        $content = @file_get_contents($this->filename);

        if (false === $content) {
            throw new InvalidArgumentException(sprintf('Cannot access "%s" to read the JSON file', $this->filename));
        }

        $content = json_decode($content, true);

        if (JSON_ERROR_NONE !== json_last_error()) {
            throw new InvalidArgumentException(sprintf('Cannot read the JSON content: %s', json_last_error_msg()));
        }

        return \is_array($content) ? $content : [];
    }