`NullPointerException`.
 *  Fix: Include a backwards-compatible `OkHttp-Response-Source` header with
    `OkUrlFactory `responses.
 *  Fix: Don't include a default User-Agent header in requests made with the Call
    API. Requests made with OkUrlFactory will continue to have a default user
    agent.
 *  New: Guava-like API to create headers:

    ```java

OkHttp 1.x Change Log
=====================

## Version 1.6.0

_2014-05-23_

 * Offer bridges to make it easier to migrate from OkHttp 1.x to OkHttp 2.0.
   This adds `OkUrlFactory`, `Cache`, and `@Deprecated` annotations for APIs
   dropped in 2.0.

## Version 1.5.4

_2014-04-14_

 * Drop ALPN support in Android. There's a concurrency bug in all
   currently-shipping versions.

    3.14 we detect this problem but the exception was not helpful.

## Version 3.14.0

_2019-03-14_

 *  **This release deletes the long-deprecated `OkUrlFactory` and `OkApacheClient` APIs.** These
    facades hide OkHttp's implementation behind another client's API. If you still need this please
    copy and paste [ObsoleteUrlFactory.java][obsolete_url_factory] or