By default, OkHttp will attempt a `MODERN_TLS` connection.  However by configuring the client connectionSpecs you can allow a fall back to `COMPATIBLE_TLS` connection if the modern configuration fails.

```java
OkHttpClient client = new OkHttpClient.Builder()
    .connectionSpecs(Arrays.asList(ConnectionSpec.MODERN_TLS, ConnectionSpec.COMPATIBLE_TLS))
    .build();
```

pragmatic caching behaviour, following common real-world browser like Firefox/Chrome and 
server behaviour when ambiguous.

# Basic Usage

```kotlin
  private val client: OkHttpClient = OkHttpClient.Builder()
      .cache(Cache(
          directory = File(application.cacheDir, "http_cache"),
          // $0.05 worth of phone storage in 2020
          maxSize = 50L * 1024L * 1024L // 50 MiB
      ))

import java.io.IOException
import java.net.ProtocolException
import java.util.concurrent.TimeUnit.MILLISECONDS
import okhttp3.Headers
import okhttp3.Headers.Companion.headersOf
import okhttp3.HttpUrl
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.Response
import okhttp3.internal.checkOffsetAndCount
import okhttp3.internal.connection.BufferedSocket
import okhttp3.internal.discard
import okhttp3.internal.headersContentLength

import kotlin.time.Duration
import okhttp3.Dispatcher
import okhttp3.EventListener
import okhttp3.Headers
import okhttp3.HttpUrl
import okhttp3.HttpUrl.Companion.defaultPort
import okhttp3.OkHttpClient
import okhttp3.Response
import okhttp3.internal.http2.Header
import okio.Buffer
import okio.BufferedSource
import okio.Source

/** GMT and UTC are equivalent for our purposes. */
@JvmField

      builder.eventListenerFactory(LoggingEventListener.Factory(logger))
    }
    return builder.build()
  }

  fun close() {
    val okHttpClient = client as OkHttpClient
    okHttpClient.connectionPool.evictAll() // Close any persistent connections.
    okHttpClient.dispatcher.executorService.shutdownNow()
  }

  companion object {
    internal const val NAME = "okcurl"
    internal const val DEFAULT_TIMEOUT = -1

package okhttp3.recipes;

import java.io.IOException;
import java.security.cert.Certificate;
import okhttp3.CertificatePinner;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public final class CertificatePinning {
  private final OkHttpClient client = new OkHttpClient.Builder()
      .certificatePinner(
          new CertificatePinner.Builder()

import mockwebserver3.junit5.StartStop
import org.junit.jupiter.api.Test

class DispatcherCleanupTest {
  @StartStop
  private val server = MockWebServer()

  @Test
  fun testFinish() {
    val okhttp = OkHttpClient()
    val callback =
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {}

        override fun onResponse(
          call: Call,

 * limitations under the License.
 */
package okhttp3.recipes;

import java.io.IOException;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public final class AccessHeaders {
  private final OkHttpClient client = new OkHttpClient();

  public void run() throws Exception {
    Request request = new Request.Builder()

import java.io.IOException;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.Headers;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;

public final class AsynchronousGet {
  private final OkHttpClient client = new OkHttpClient();

  public void run() throws Exception {
    Request request = new Request.Builder()

import com.squareup.moshi.JsonAdapter;
import com.squareup.moshi.Moshi;
import java.io.IOException;
import java.util.Map;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public final class ParseResponseWithMoshi {
  private final OkHttpClient client = new OkHttpClient();
  private final Moshi moshi = new Moshi.Builder().build();
  private final JsonAdapter<Gist> gistJsonAdapter = moshi.adapter(Gist.class);