} 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(

  @Throws(IOException::class)
  fun connectionPreface() {
    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()
    }
  }

      }
    } 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()}")
      }

          writeHttpResponse(socket, response)
          reuseSocket = false
        } else {
          writeHttpResponse(socket, response)
        }

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

    @Override
    public void handleException(Throwable exception, SubscriberExceptionContext context) {
      Logger logger = logger(context);
      if (logger.isLoggable(Level.SEVERE)) {
        logger.log(Level.SEVERE, message(context), exception);
      }
    }

    private static Logger logger(SubscriberExceptionContext context) {