// is an STS request for a claim based IDP (if one is present) and set
	// roleArn = openid.DummyRoleARN.
	//
	// Currently, we do not support multiple claim based IDPs, as there is no
	// defined parameter to disambiguate the intended IDP in this STS request.
	roleArn := openid.DummyRoleARN
	roleArnStr := r.Form.Get(stsRoleArn)
	if roleArnStr != "" {
		var err error
		roleArn, _, err = globalIAMSys.GetRolePolicy(roleArnStr)