upgrading OkHttp. With this change it is now a regular Java class with
    enum-like constants. Application code that uses enum methods on cipher
    suites (`ordinal()`, `name()`, etc.) will break with this change.

 *  Fix: `CertificatePinner` now matches canonicalized hostnames. Previously
    this was case sensitive. This change should also make it easier to configure

## Supported Versions

| Version | Supported           | Notes                                        |
| ------- | ------------------- | -------------------------------------------- |
| 5.x     | ✅                  | APIs subject to change in alpha releases.    |
| 4.x     | ✅                  | Android 5.0+ (API level 21+) and on Java 8+. |
| 3.x     | ❌ Ended 2021-12-31 | Android 2.3+ (API level 9+) and Java 7+.     |


## Reporting a Vulnerability

 * of which connections to keep open for future use.
 *
 * @constructor Create a new connection pool with tuning parameters appropriate for a single-user
 * application. The tuning parameters in this pool are subject to change in future OkHttp releases.
 * Currently this pool holds up to 5 idle connections which will be evicted after 5 minutes of
 * inactivity.
 */
class ConnectionPool internal constructor(

    ```

### Per-call Configuration ([.kt][PerCallSettingsKotlin], [.java][PerCallSettingsJava])

    assertNotSame(
      client.routeDatabase,
      OkHttpClient.Builder()
        .build()
        .routeDatabase,
    )

    // same client with no change affecting route db
    assertSame(
      client.routeDatabase,
      client.newBuilder()
        .build()
        .routeDatabase,
    )
    assertSame(
      client.routeDatabase,

need to customize SSL, do so for your specific OkHttpClient instance only.

##### Synthetic headers have changed

Previously OkHttp added a synthetic response header, `OkHttp-Selected-Transport`. It
has been replaced with a new synthetic header, `OkHttp-Selected-Protocol`.

##### Changes

 * New: Support for `HTTP-draft-09/2.0`.
 * New: Support for `spdy/3.1`. Dropped support for `spdy/3`.

      streamId: Int,
      windowSizeIncrement: Long,
    )

    /**
     * Called when reading a headers or priority frame. This may be used to change the stream's
     * weight from the default (16) to a new value.
     *
     * @param streamId stream which has a priority change.
     * @param streamDependency the stream ID this stream is dependent on.
     * @param weight relative proportion of priority in `[1..256]`.

      Header("if-none-match", ""),
      Header("if-range", ""),
      Header("if-unmodified-since", ""),
      Header("last-modified", ""),
      Header("link", ""),
      Header("location", ""),
      Header("max-forwards", ""),
      Header("proxy-authenticate", ""),
      Header("proxy-authorization", ""),
      Header("range", ""),
      Header("referer", ""),
      Header("refresh", ""),

#### Internal API changes

The `okhttp3.internal` package is not a published API and we change it frequently without warning.
Depending on code in this package is bad and will cause you problems with any upgrade! But the 4.x
will be particularly painful to naughty developers that import from this package! We changed a lot
to take advantage of sweet Kotlin features.

#### Credentials.basic()

  private val writerQueue = taskRunner.newQueue()

  /** Ensures push promise callbacks events are sent in order per stream. */
  private val pushQueue = taskRunner.newQueue()

  /** Notifies the listener of settings changes. */
  private val settingsListenerQueue = taskRunner.newQueue()

  /** User code to run in response to push promise events. */
  private val pushObserver: PushObserver = builder.pushObserver