public function addCert(string $type, string $pathOrContent, bool $isContent = false): ConfigInterface
    {
        $type = mb_strtolower($type);
        $this->throwIfNotInArray($type, self::CERTS);
        if (true === $isContent) {
            $this->_certs[$type]['content'] = $pathOrContent;
        } else {
            $this->_certs[$type]['path'] = $pathOrContent;
        }
        return $this;
    }