private void copyTrackingHeaders(HttpRequest httpRequest) throws RestServiceException {
    for (String header : RestUtils.TrackingHeaders.TRACKING_HEADERS) {
      restResponseChannel.setHeader(header, httpRequest.headers().get(header));
    }
  }
Copies tracking headers from request to response.
@param httpRequest the {@link HttpRequest} to copy headers from.
ambry-rest/src/test/java/com/github/ambry/rest/NettyResponseChannelTest.java