protected function buildAuthorizationHeader(RequestInterface $request, array $customHeaders = [])
    {
        $authHeaderBuilder = new AuthorizationHeaderBuilder($request, $this->key, $this->digest);
        $authHeaderBuilder->setRealm($this->realm);
        $authHeaderBuilder->setId($this->key->getId());
        $authHeaderBuilder->setCustomHeaders($customHeaders);

        return $authHeaderBuilder->getAuthorizationHeader();
    }