All the options depends on guzzle capabilities. See the .
If you need to use a proxy to access to the OP (see the doc ) :
$client = new Svgta\OidcClient\init();
//...
$client->request->setHttpProxy('http://proxyUri:proxyPort');
$client->request->setHttpsProxy('http://proxyUri:proxyPort');
//the proxy is a string
$client->request->setNoProxy(['.myDomain', '.myOtherDomain']);
// the list is an array of domains that don't use proxy if http proxy and https proxy are set