With a few small exceptions (below), OkHttp 4.x is both binary- and Java source-compatible with
OkHttp 3.x. You can use an OkHttp 4.x .jar file with applications or libraries built for OkHttp 3.x.

OkHttp is **not** source-compatible for Kotlin callers, but upgrading should be automatic thanks to
Kotlin’s powerful deprecation features. Most developers should be able to use IntelliJ’s _Code
Cleanup_ for a safe and fast upgrade.

ciphers.

When negotiating a connection to an HTTPS server, OkHttp needs to know which [TLS versions](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-tls-version/) and [cipher suites](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-cipher-suite/) to offer. A client that wants to maximize connectivity would include obsolete TLS versions and weak-by-design cipher suites. A strict client that wants to maximize security would be limited to only the latest TLS version and strongest cipher suites....

    configure<ApiValidationExtension> {
      ignoredPackages += "okhttp3.logging.internal"
      ignoredPackages += "mockwebserver3.internal"
      ignoredPackages += "okhttp3.internal"
      ignoredPackages += "mockwebserver3.junit5.internal"
      ignoredPackages += "okhttp3.brotli.internal"
      ignoredPackages += "okhttp3.sse.internal"
      ignoredPackages += "okhttp3.tls.internal"
    }
  }
}

 *  New: Create a JPMS-compatible artifact for `JavaNetCookieJar`. Previously, multiple OkHttp
    artifacts defined classes in the `okhttp3` package, but this is forbidden by the Java module
    system. We've fixed this with a new package (`okhttp3.java.net.cookiejar`) and a new artifact,
    `com.squareup.okhttp3:okhttp-java-net-cookiehandler`. (The original artifact now delegates to
    this new one.)

    ```kotlin

    keep all of your OkHttp artifacts on the same version, even if they're declared via transitive
    dependencies. You can even omit versions when declaring other OkHttp dependencies.

    ```kotlin
    dependencies {
       api(platform("com.squareup.okhttp3:okhttp-bom:4.4.0"))
       api("com.squareup.okhttp3:okhttp")              // No version!

To prevent a response from using the cache, use [`CacheControl.FORCE_NETWORK`](http://square.github.io/okhttp/4.x/okhttp/okhttp3/-cache-control/-f-o-r-c-e_-n-e-t-w-o-r-k/). To prevent it from using the network, use [`CacheControl.FORCE_CACHE`](http://square.github.io/okhttp/4.x/okhttp/okhttp3/-cache-control/-f-o-r-c-e_-c-a-c-h-e/). Be warned: if you use `FORCE_CACHE` and the response requires the network, OkHttp will return a `504 Unsatisfiable Request` response.

    cachedResponse: Response,
  ) {
  }

  /**
   * Invoked when OkHttp decides whether to retry after a connectivity failure.
   *
   * OkHttp won't retry when it is configured not to:
   *
   *  * If retries are forbidden with [OkHttpClient.retryOnConnectionFailure]. (OkHttp's defaults
   *    permit retries.)
   *  * If OkHttp already attempted to transmit the request body, and [RequestBody.isOneShot] is
   *    true.

 *  **URLConnection support has moved to the okhttp-urlconnection module.**
    If you're upgrading from 1.x, this change will impact you. You will need to
    add the `okhttp-urlconnection` module to your project and use the
    `OkUrlFactory` to create new instances of `HttpURLConnection`:

    ```java
    // OkHttp 1.x:
    HttpURLConnection connection = client.open(url);

    // OkHttp 2.x:

import mockwebserver3.junit5.StartStop
import okhttp3.HttpUrl
import okhttp3.Interceptor
import okhttp3.MediaType
import okhttp3.MediaType.Companion.toMediaType
import okhttp3.OkHttpClient
import okhttp3.Protocol
import okhttp3.RecordingHostnameVerifier
import okhttp3.Request
import okhttp3.RequestBody
import okhttp3.RequestBody.Companion.toRequestBody
import okhttp3.logging.HttpLoggingInterceptor.Level

import mockwebserver3.junit5.StartStop
import okhttp3.Interceptor
import okhttp3.OkHttpClient
import okhttp3.OkHttpClientTestRule
import okhttp3.Protocol
import okhttp3.RecordingEventListener
import okhttp3.RecordingHostnameVerifier
import okhttp3.Request
import okhttp3.Response
import okhttp3.TestLogHandler
import okhttp3.TestUtil.assumeNotWindows
import okhttp3.TestUtil.repeat
import okhttp3.WebSocket
import okhttp3.WebSocketListener