import this and we want to ease upgrades for their users.


## Version 4.0.0-RC2

_2019-06-21_

 *  New: Require Kotlin 1.3.40.
 *  New: Change the Kotlin API from `File.toRequestBody()` to `File.asRequestBody()` and
    `BufferedSource.toResponseBody()` to `BufferedSource.asResponseBody()`. If the returned value
    is a view of what created it, we use _as_.
 *  Fix: Permit response codes of zero for compatibility with OkHttp 3.x.