*/
  private val enforceOrder: Boolean = true,
) : ConnectionListener() {
  val eventSequence: Deque<ConnectionEvent> = ConcurrentLinkedDeque()

  private val forbiddenLocks = mutableSetOf<Any>()

  /** The timestamp of the last taken event, used to measure elapsed time between events. */
  private var lastTimestampNs: Long? = null

  init {
    val map = mutableMapOf<X500Principal, MutableSet<X509Certificate>>()
    for (caCert in caCerts) {
      map.getOrPut(caCert.subjectX500Principal) { mutableSetOf() }.add(caCert)
    }
    this.subjectToCaCerts = map
  }

  override fun findByIssuerAndSignature(cert: X509Certificate): X509Certificate? {
    val issuer = cert.issuerX500Principal

 * a specific IP address or proxy server, that failure is remembered and alternate routes are
 * preferred.
 */
class RouteDatabase {
  private val _failedRoutes = mutableSetOf<Route>()

  val failedRoutes: Set<Route>
    @Synchronized get() = _failedRoutes.toSet()

  /** Records a failure connecting to [failedRoute]. */
  @Synchronized fun failed(failedRoute: Route) {