### [Connections](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-connection/)

When you request a URL with OkHttp, here's what it does:

 1. It uses the URL and configured OkHttpClient to create an **address**. This address specifies how we'll connect to the webserver.
 2. It attempts to retrieve a connection with that address from the **connection pool**.

   *
   * By default OkHttp will attempt to retransmit request bodies when the original request fails
   * due to any of:
   *
   *  * A stale connection. The request was made on a reused connection and that reused connection
   *    has since been closed by the server.
   *  * A client timeout (HTTP 408).
   *  * A authorization challenge (HTTP 401 and 407) that is satisfied by the [Authenticator].

    health check fails.


## Version 2.7.0

_2015-12-13_

 *  **Rewritten connection management.** Previously OkHttp's connection pool
    managed both idle and active connections for HTTP/2, but only idle
    connections for HTTP/1.x. With this update the connection pool manages both
    idle and active connections for everything. OkHttp now detects and warns on

    override val call: Call,
    val connection: Connection,
  ) : CallEvent()

  data class ConnectionReleased(
    override val timestampNs: Long,
    override val call: Call,
    val connection: Connection,
  ) : CallEvent() {
    override fun closes(event: CallEvent): Boolean = event is ConnectionAcquired && call == event.call && connection == event.connection
  }

  data class CallStart(

          clientTestRule.wrap(
            object : EventListener() {
              override fun connectionAcquired(
                call: Call,
                connection: Connection,
              ) {
                val sslSocket = connection.socket() as SSLSocket

                sessionIds.add(
                  sslSocket.session.id
                    .toByteString()
                    .hex(),

        final HttpURLConnection connection = (HttpURLConnection) (proxy != null ? u.openConnection(proxy) : u.openConnection());
        if (sslSocketFactory != null && connection instanceof HttpsURLConnection) {
            ((HttpsURLConnection) connection).setSSLSocketFactory(sslSocketFactory);
        }
        return connection;
    }

    /**

    routePlanner.defaultConnectionIdleAtNanos = expireSooner

    // Turn it into an http/2 connection that supports 5 concurrent streams
    // which can satisfy a larger policy
    val connection = routePlanner.plans.first().connection
    val http2Connection = connectHttp2(peer, connection, 5)
    setPolicy(pool, address, AddressPolicy(5))
    assertThat(pool.connectionCount()).isEqualTo(1)

the work, and under which the third party grants, to any of the
parties who would receive the covered work from you, a discriminatory
patent license (a) in connection with copies of the covered work
conveyed by you (or copies made from those copies), or (b) primarily
for and in connection with specific products or compilations that
contain the covered work, unless you entered into that arrangement,

 * server.
 *
 * ## Preemptive Authentication
 *
 * To make HTTPS calls using an HTTP proxy server OkHttp must first negotiate a connection with
 * the proxy. This proxy connection is called a "TLS Tunnel" and is specified by
 * [RFC 2817][1]. The HTTP CONNECT request that creates this tunnel connection is special: it
 * does not participate in any [interceptors][Interceptor] or [event listeners][EventListener]. It

import okhttp3.internal.indexOf
import okhttp3.internal.intersect

/**
 * Specifies configuration for the socket connection that HTTP traffic travels through. For `https:`
 * URLs, this includes the TLS version and cipher suites to use when negotiating a secure
 * connection.
 *
 * The TLS versions configured in a connection spec are only be used if they are also enabled in the