*  Fix: Don't crash with an `InaccessibleObjectException` when running on JDK17+ with strong
    encapsulation enabled.
 *  Fix: Strictly verify hostnames used with OkHttp's `HostnameVerifier`. Programs that make direct
    manual calls to `HostnameVerifier` could be defeated if the hostnames they pass in are not
    strictly ASCII. This issue is tracked as [CVE-2021-0341].


## Version 4.9.1

_2021-01-30_

  /**
   * Returns the last value corresponding to the specified field parsed as an HTTP date, or null if
   * either the field is absent or cannot be parsed as a date.
   */
  @IgnoreJRERequirement // Only programs that already have Instant will use this.
  fun getInstant(name: String): Instant? {
    return getDate(name)?.toInstant()
  }

  /** Returns the number of field values. */
  @get:JvmName("size")
  val size: Int

keeping the package name the same: `okhttp3`!

There are three kinds of compatibility we’re tracking:

 * **Binary compatibility** is the ability to compile a program against OkHttp 3.x, and then to run
   it against OkHttp 4.x. We’re using the excellent [japicmp][japicmp] library via its
   [Gradle plugin][japicmp_gradle] to enforce binary compatibility.

Most applications should call `new OkHttpClient()` exactly once, configure it with their cache, and use that same instance everywhere. Otherwise the two cache instances will stomp on each other, corrupt the response cache, and possibly crash your program.

Response caching uses HTTP headers for all configuration. You can add request headers like `Cache-Control: max-stale=3600` and OkHttp's cache will honor them. Your webserver configures how long responses are cached with its own response...