Login to a VclHost using SAML authentication

Hi there,

does anyone know how a SAML authentication is supposed to work for a SHARED_SESSION login? I'd like to be able to login a user given a username, organization name and an already existing SAML token... I'd expect it to work like this:

var host = VclHostManager.createHost();
host.url = "https://:443";
host.enabled = true;
host.sessionMode = VclHostSessionMode.SHARED_SESSION;
host.organization = "some-org"; // this organization has SSO enabled & configured, login via SAML works as expected via vCloud Director
host.setUsername("some user");
host.useSamlAuthentication = true;
host.setSamlTokenCallback(samlAction);
host.login();

The samlAction never gets called, instead I get an exception that reads "org.opensaml.saml2.core.impl.ResponseImpl cannot be cast to org.opensaml.saml2.core.Assertion". Has anyone done this already and can shed some light on this? Regards, Igor