title: X-Amzn-Trace-Id not present in response header when response status is other than 200
body: <p>I am using X-Ray tracing in API Gateway and Lambda authorizer. Inside the authorizer, I am calling two HTTP URLs. </p>
  
  <ul>
  <li><p>When I give invalid URL for one http call, I am throwing callback ("unauthorized") from lambda authorizer. Hence, the response status will be 401. When I look into the response headers, I couldn't find X-Amzn-Trace-Id. </p></li>
  <li><p>When the URL is valid and status is 200, <code>X-Amzn-Trace-Id</code> is seen in response headers. </p></li>
  </ul>
  
  <p>Is there anyway to retrieve <code>X-Amzn-Trace-Id</code> irrespective of the status (always)?</p>