private function getRedirectUriWithState(?string $state = null): string
    {
        if (null === $state) {
            return $this->redirectUri;
        }

        $sep = false === strpos($this->redirectUri, '?') ? '?' : '&';

        return $this->redirectUri.$sep.'state='.$state;
    }
private function getRedirectUriWithState(?string $state = null): string
    {
        if (null === $state) {
            return $this->redirectUri;
        }

        $sep = false === strpos($this->redirectUri, '?') ? '?' : '&';

        return $this->redirectUri.$sep.'state='.$state;
    }
@param string|null $state

@return string