}
        addAll(listOf("ConnectionAcquired", "ConnectionReleased", "CallEnd"))
      }

    assertThat(events2).isEqualTo(expectedEvents2)
  }

  private fun isConnectionEvent(it: CallEvent?) =
    it is CallStart ||
      it is CallEnd ||
      it is ConnectStart ||
      it is ConnectEnd ||
      it is ConnectionAcquired ||
      it is ConnectionReleased ||
      it is Canceled ||

    }

    @Override public void connectionAcquired(Call call, Connection connection) {
      printEvent("connectionAcquired");
    }

    @Override public void connectionReleased(Call call, Connection connection) {
      printEvent("connectionReleased");
    }

    @Override public void requestHeadersStart(Call call) {
      printEvent("requestHeadersStart");
    }

    call: Call,
    connection: Connection,
  ) {
    logWithTime("connectionAcquired: $connection")
  }

  override fun connectionReleased(
    call: Call,
    connection: Connection,
  ) {
    logWithTime("connectionReleased")
  }

  override fun requestHeadersStart(call: Call) {
    logWithTime("requestHeadersStart")
  }

  override fun requestHeadersEnd(

    }

    @Override public void connectionAcquired(Call call, Connection connection) {
      printEvent("connectionAcquired");
    }

    @Override public void connectionReleased(Call call, Connection connection) {
      printEvent("connectionReleased");
    }

    @Override public void requestHeadersStart(Call call) {
      printEvent("requestHeadersStart");
    }

   */
  open fun connectionAcquired(
    connection: Connection,
    call: Call,
  ) {}

  /**
   * Invoked when a call no longer uses a connection.
   */
  open fun connectionReleased(
    connection: Connection,
    call: Call,
  ) {}

  /**
   * Invoked when a connection is marked for no new exchanges.
   */
  open fun noNewExchanges(connection: Connection) {}

  ) : ConnectionEvent()

  data class ConnectionAcquired(
    override val timestampNs: Long,
    override val connection: Connection,
    val call: Call,
  ) : ConnectionEvent()

  data class ConnectionReleased(
    override val timestampNs: Long,
    override val connection: Connection,
    val call: Call,
  ) : ConnectionEvent() {
    override fun closes(event: ConnectionEvent): Boolean =

      for (delegate in eventListeners) {
        delegate.connectionAcquired(call, connection)
      }
    }

    override fun connectionReleased(
      call: Call,
      connection: Connection,
    ) {
      for (delegate in eventListeners) {
        delegate.connectionReleased(call, connection)
      }
    }

    override fun requestHeadersStart(call: Call) {
      for (delegate in eventListeners) {

import okhttp3.CallEvent.CallEnd
import okhttp3.CallEvent.CallStart
import okhttp3.CallEvent.ConnectEnd
import okhttp3.CallEvent.ConnectStart
import okhttp3.CallEvent.ConnectionAcquired
import okhttp3.CallEvent.ConnectionReleased
import okhttp3.CallEvent.DnsEnd
import okhttp3.CallEvent.DnsStart
import okhttp3.CallEvent.FollowUpDecision
import okhttp3.CallEvent.ProxySelectEnd
import okhttp3.CallEvent.ProxySelectStart

  override fun connectionAcquired(
    connection: Connection,
    call: Call,
  ) {
    logEvent(ConnectionEvent.ConnectionAcquired(System.nanoTime(), connection, call))
  }

  override fun connectionReleased(
    connection: Connection,
    call: Call,
  ) {
    if (eventSequence.find { it is ConnectionEvent.ConnectStart && it.connection == connection } != null && connection is RealConnection) {

response only if the response code is HTTP/1.1 304 Not Modified.

 - CallStart
 - **CacheConditionalHit**
 - ConnectionAcquired
 - ... Standard Events...
 - ResponseBodyEnd _(0 bytes)_
 - **CacheHit**
 - ConnectionReleased
 - CallEnd

## Cache directory

The cache directory must be exclusively owned by a single instance.

Deleting the cache when it is no longer needed can be done.  However this may delete the purpose of the cache