Do not use these experimental APIs in modules that may be executed using a version of OkHttp
    different from the version that the module was compiled with. Do not use them in published
    libraries. Do not use them if you aren't willing to track changes to them.

 *  Breaking: Drop support for Kotlin Multiplatform.

    We planned to support multiplatform in OkHttp 5.0, but after building it, we weren't happy with

   without changing `.kt` files.

With a few small exceptions (below), OkHttp 4.x is both binary- and Java source-compatible with
OkHttp 3.x. You can use an OkHttp 4.x .jar file with applications or libraries built for OkHttp 3.x.

OkHttp is **not** source-compatible for Kotlin callers, but upgrading should be automatic thanks to
Kotlin’s powerful deprecation features. Most developers should be able to use IntelliJ’s _Code