}
    } else {
      // The server reads the CONNECTION_PREFACE byte string.
      val connectionPreface = source.readByteString(CONNECTION_PREFACE.size.toLong())
      if (logger.isLoggable(FINE)) logger.fine(format("<< CONNECTION ${connectionPreface.hex()}"))
      if (CONNECTION_PREFACE != connectionPreface) {
        throw IOException("Expected a connection header but was ${connectionPreface.utf8()}")
      }

    } catch (ConflictingRequirementsException e) {
      throw new RuntimeException(e);
    }
    if (!features.containsAll(requirements.getPresentFeatures())) {
      if (logger.isLoggable(FINER)) {
        Set<Feature<?>> missingFeatures = copyToSet(requirements.getPresentFeatures());
        missingFeatures.removeAll(features);
        logger.finer(
            Platform.format(

    } catch (ConflictingRequirementsException e) {
      throw new RuntimeException(e);
    }
    if (!features.containsAll(requirements.getPresentFeatures())) {
      if (logger.isLoggable(FINER)) {
        Set<Feature<?>> missingFeatures = copyToSet(requirements.getPresentFeatures());
        missingFeatures.removeAll(features);
        logger.finer(
            Platform.format(

  fun connectionPreface() {
    this.withLock {
      if (closed) throw IOException("closed")
      if (!client) return // Nothing to write; servers don't send connection headers!
      if (logger.isLoggable(FINE)) {
        logger.fine(format(">> CONNECTION ${CONNECTION_PREFACE.hex()}"))
      }
      sink.write(CONNECTION_PREFACE)
      sink.flush()
    }
  }

   * should be used specifically for [java.io.Closeable] objects and in conjunction with
   * [logCloseableLeak].
   */
  open fun getStackTraceForCloseable(closer: String): Any? {
    return when {
      logger.isLoggable(Level.FINE) -> Throwable(closer) // These are expensive to allocate.
      else -> null
    }
  }

  open fun logCloseableLeak(
    message: String,
    stackTrace: Any?,
  ) {

        handleWebSocketUpgrade(socket, source, sink, request, response)
        reuseSocket = false
      } else {
        writeHttpResponse(socket, sink, response)
      }

      if (logger.isLoggable(Level.FINE)) {
        logger.fine(
          "${this@MockWebServer} received request: $request and responded: $response",
        )
      }