in CachingProxy/src/CachingProxy.cs [422:431]
private static void SetCachedResponseHeader(HttpContext context, ResponseCache.Entry entry)
{
context.Response.Headers[CachingProxyConstants.CachedStatusHeader] = ((int) entry.StatusCode).ToString();
context.Response.Headers[CachingProxyConstants.CachedUntilHeader] = entry.CacheUntil.ToString("R");
// Cache successful responses indefinitely
// as we assume content won't be changed under a fixed url
if (entry.StatusCode.IsSuccessStatusCode())
AddEternalCachingControl(context);
}