## Version 4.2.1

_2019-10-02_

 *  Fix: In 4.1.0 we introduced a performance regression that prevented connections from being
    pooled in certain situations. We have good test coverage for connection pooling but we missed
    this because it only occurs if you have proxy configured and you share a connection pool among
    multiple `OkHttpClient` instances.

   certificate pinning, you must be very careful to avoid [bricking][brick]
   your app. You'll need to pin both the top-level domain and the `*.` domain
   for full coverage.

    ```java
     client.setCertificatePinner(new CertificatePinner.Builder()
         .add("publicobject.com",   "sha1/DmxUShsZuNiqPQsX2Oi9uv2sCnw=")