public function challenge(RequestInterface $request, ResponseInterface $response)
    {
        foreach ($this->backends as $backend) {
            $backend->challenge($request, $response);
        }
    }
public function challenge(RequestInterface $request, ResponseInterface $response)
    {
        foreach ($this->backends as $backend) {
            $backend->challenge($request, $response);
        }
    }
public function challenge ( RequestInterface $ request , ResponseInterface $ response ) { foreach ( $ this -> backends as $ backend ) { $ backend -> challenge ( $ request , $ response ) ; } }
This method sends authentication challenges to the user.

This method will for example cause a HTTP Basic backend to set a
WWW-Authorization header, indicating to the client that it should
authenticate.

@param RequestInterface  $request
@param ResponseInterface $response

@return array
This method sends authentication challenges to the user .