final CloseableHttpResponse backendResponse = backend.execute(
route, conditionalRequest, context, execAware);
try {
final Date responseDate = getCurrentDate();
backendResponse.addHeader("Via", generateViaHeader(backendResponse));
if (backendResponse.getStatusLine().getStatusCode() != HttpStatus.SC_NOT_MODIFIED) {
return handleBackendResponse(
route, request, context, execAware,
requestDate, responseDate, backendResponse);