your listener if OkHttp has decided to make a follow-up request. Some common follow-ups are
    authentication challenges and redirects.

 *  New: Handy constants for `Headers.EMPTY`, `RequestBody.EMPTY`, and `ResponseBody.EMPTY`.

 *  New: OkHttp now calls `StrictMode.noteSlowCall()` when initializing TLS on Android. Use
    `StrictMode` to detect if your `OkHttpClient` is being initialized on the main thread.