private var http2Connection: Http2Connection? = null

  internal val lock: ReentrantLock = ReentrantLock()

  // These properties are guarded by [lock].

  /**
   * If true, no new exchanges can be created on this connection. It is necessary to set this to
   * true when removing a connection from the pool; otherwise a racing caller might get it from the

    initialization order of companion objects.


## Version 4.7.1

_2020-05-18_

 *  Fix: Pass the right arguments in the trust manager created for `addInsecureHost()`. Without the
    fix insecure hosts crash with an `IllegalArgumentException` on Android.


## Version 4.7.0

_2020-05-17_

    logger.log(logLevel, message, t)
  }

  open fun isCleartextTrafficPermitted(hostname: String): Boolean = true

  /**
   * Returns an object that holds a stack trace created at the moment this method is executed. This
   * should be used specifically for [java.io.Closeable] objects and in conjunction with
   * [logCloseableLeak].
   */
  open fun getStackTraceForCloseable(closer: String): Any? {

/**
 * An OkHttp interceptor which logs request and response information. Can be applied as an
 * [application interceptor][OkHttpClient.interceptors] or as a [OkHttpClient.networkInterceptors].
 *
 * The format of the logs created by this class should not be considered stable and may
 * change slightly between releases. If you need a stable logging format, use your own interceptor.
 */
class HttpLoggingInterceptor
  @JvmOverloads
  constructor(

    assertContent("This comes after a busted connection", response2)

    // Check that a fresh connection was created, either immediately or after attempting reuse.
    // We know that a fresh connection was created if the server recorded a request with sequence
    // number 0. Since the client may have attempted to reuse the broken connection just before

    assertThat(source1.readUtf8(10)).isEqualTo("abcdefghij")
    assertThat(source1.exhausted()).isTrue()
    source1.close()
    assertThat(relay1.isClosed).isTrue()

    // Since relay1 is closed, new sources cannot be created.
    assertThat(relay1.newSource()).isNull()
    val relay2 = read(file)
    assertThat(relay2.metadata()).isEqualTo(metadata)
    val source2 = relay2.newSource()!!.buffer()

OkHttpClient uses a connection pool. Its job is to maintain a reference to all open connections. When an HTTP request is started, OkHttp will attempt to reuse an existing connection from the pool. If there are no existing connections, a new one is created and put into the connection pool. For HTTP/2, the connection can be reused immediately. For HTTP/1, the request must be completed before it can be reused.

Since HTTP requests frequently happen in parallel, connection pooling must be thread-safe....

This [sample factory](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEvents.java) creates a unique ID for each call and uses that ID to differentiate calls in log messages.

```java

    private const val FILE_HEADER_SIZE = 32L

    /**
     * Creates a new relay that reads a live stream from [upstream], using [file] to share that data
     * with other sources.
     *
     * **Warning:** callers to this method must immediately call [newSource] to create a source and
     * close that when they're done. Otherwise a handle to [file] will be leaked.
     */

package okhttp3

import javax.net.ssl.SSLSocket
import javax.net.ssl.SSLSocketFactory
import okhttp3.FallbackTestClientSocketFactory.Companion.TLS_FALLBACK_SCSV

/**
 * An SSLSocketFactory that delegates calls. Sockets created by the delegate are wrapped with ones
 * that will not accept the [TLS_FALLBACK_SCSV] cipher, thus bypassing server-side fallback
 * checks on platforms that support it. Unfortunately this wrapping will disable any