### Version 4.0 * Support RxJava-style Observers. * Return type can be `Observable` for an async equiv of `Iterable`. * `Observer` replaces `IncrementalCallback` and is passed to `Observable.subscribe()`. * On `Subscription.unsubscribe()`, `Observer.onNext()` will stop being called. ### Version 3.1 * Log when an http request is retried or a response fails due to an IOException. ### Version 3.0 * Added support for asynchronous callbacks via `IncrementalCallback` and `IncrementalDecoder.TextStream`. * Wire is now Logger, with configurable Logger.Level. * Added `feign-gson` codec, used via `new GsonModule()` * changed codec to be similar to [WebSocket JSR 356](http://docs.oracle.com/javaee/7/api/javax/websocket/package-summary.html) * Decoder is now `Decoder.TextStream` * BodyEncoder is now `Encoder.Text` * FormEncoder is now `Encoder.Text