Find SSO endpoint prioritize by binding.

Not very important now tht we only specify one allowed binding,
but remains correct when more bindings might be added in the future.

Author: thijskh

lib/Auth/Process/SFO.php

@@ -111,7 +111,7 @@ private function startSFO(SimpleSAML_Configuration $idpMetadata, \SAML2\XML\saml
         SimpleSAML\Logger::debug('Sending SAML 2 SFO AuthnRequest for ' . $nameid->value .  ' to ' .
             var_export($idpMetadata->getString('entityid'), true). ' with id ' . $ar->getId());
 
-        $dst = $idpMetadata->getDefaultEndpoint('SingleSignOnService',
+        $dst = $idpMetadata->getEndpointPrioritizedByBinding('SingleSignOnService',
                 [ \SAML2\Constants::BINDING_HTTP_REDIRECT ]
             );