Xitrum websocket connection issue

Boot.scala

package quickstart

import xitrum.Server

object Boot {
  def main(args: Array[String]) {
    Server.start()
    Server.stopAtShutdown()
  }
}

import xitrum.annotation.WEBSOCKET
import xitrum.{WebSocketAction, WebSocketText}
@WEBSOCKET("echo")
class EchoWebSocketActor extends WebSocketAction {
  def execute() {
    log.debug("onOpen")
    context.become {
      case WebSocketText(text) =>
        log.info("onTextMessage: " + text)
        respondWebSocketText(text.toUpperCase)
    }
  }

  override def postStop() {
    log.debug("onClose")
    super.postStop()
  }
}

build.sbt

name         := "xitrum-ws-client-test"

version      := "1.0-SNAPSHOT"

scalaVersion := "2.10.3"

resolvers += "SonatypeReleases" at "http://oss.sonatype.org/content/repositories/releases/"

libraryDependencies += "org.asynchttpclient" % "async-http-client" % "2.4.2"

Client.scala

import org.asynchttpclient.DefaultAsyncHttpClientConfig
import org.asynchttpclient.DefaultAsyncHttpClient
import org.asynchttpclient.ws.WebSocketUpgradeHandler
import org.asynchttpclient.ws.WebSocketListener
import org.asynchttpclient.ws.WebSocket

object TestMain {
  val URL = "ws://localhost:8000/echo"

  private val client = {
    val TIMEOUT_MS = 5 * 1000
    val conf = new DefaultAsyncHttpClientConfig.Builder()
      .setConnectTimeout(TIMEOUT_MS)
      .setRequestTimeout(TIMEOUT_MS)
      .setReadTimeout(TIMEOUT_MS)
      .setConnectTimeout(TIMEOUT_MS)
      .setWebSocketMaxFrameSize(10 * 1024 * 1024)
      .build()
    new DefaultAsyncHttpClient(conf)
  }

  def main(args: Array[String]) {
    for (i <- 0 until 1000) {
      print(s"${i},")
      test()
    }
  }

  def test() {
    val l = new MyWebSocketListener
    val h = new WebSocketUpgradeHandler.Builder().addWebSocketListener(l).build()
    val ws = client.prepareGet(URL).execute(h).get()
    ws.sendCloseFrame().get()
  }

  class MyWebSocketListener extends WebSocketListener {
    override def onError(t: Throwable): Unit = {}
    override def onClose(websocket: WebSocket, code: Int, reason: String): Unit = {}
    override def onOpen(websocket: WebSocket): Unit = {}
  }
}