This is a feature parity issue between Android, iOS, and Windows Phone when using HTTPClient.
On iOS, you access the HTTP response's headers via the "responseHeaders" property, which returns them as a dictionary...
On Android and Windows Phone, you have to access the headers via the "allResponseHeaders" property instead, which returns all headers concatenated to a single string...
Add "responseHeaders" property support to Android. The way iOS is doing it (returning a dictionary) is the superior solution. (In the future, we should add support to Windows as well.)