private var source: BufferedSource?,
  private var sink: BufferedSink?,
  private val pingIntervalMillis: Int,
  internal val connectionListener: ConnectionListener,
) : Http2Connection.Listener(), Connection, ExchangeCodec.Carrier {
  private var http2Connection: Http2Connection? = null

  internal val lock: ReentrantLock = ReentrantLock()

  // These properties are guarded by [lock].

  /**

  internal val routes: List<Route>?,
  private val attempt: Int,
  private val tunnelRequest: Request?,
  internal val connectionSpecIndex: Int,
  internal val isTlsFallback: Boolean,
) : RoutePlanner.Plan, ExchangeCodec.Carrier {
  /** True if this connect was canceled; typically because it lost a race. */
  @Volatile private var canceled = false

  // These properties are initialized by connect() and never reassigned.