Lagom Server：java.lang.IllegalArgumentException

我正在拉古姆项目中创建一个模块 . 我的模块只有kafka使用者在cassandra中消费消息和存储消息事件 . 谢谢，为什么，在我的 LagomApplicationLoader 中我没有定义任何服务并使用 LagomServer.forServices() 初始化 lagomServer 为空 . 但每当我开始申请时，我都会遇到以下异常：

java.lang.IllegalArgumentException
    at com.lightbend.lagom.scaladsl.server.LagomServer$$anon$2.<init>(LagomServer.scala:35)
    at com.lightbend.lagom.scaladsl.server.LagomServer$.forServices(LagomServer.scala:31)
    at com.knoldus.consumer.impl.TwitterConsumerApplication.lagomServer$lzycompute(TwitterConsumerLoader.scala:33)
    at com.knoldus.consumer.impl.TwitterConsumerApplication.lagomServer(TwitterConsumerLoader.scala:33)
    at com.lightbend.lagom.scaladsl.server.LagomApplication.<init>(LagomApplicationLoader.scala:187)
    at com.knoldus.consumer.impl.TwitterConsumerApplication.<init>(TwitterConsumerLoader.scala:28)
    at com.knoldus.consumer.impl.TwitterConsumerLoader$$anon$1.<init>(TwitterConsumerLoader.scala:25)
    at com.knoldus.consumer.impl.TwitterConsumerLoader.loadDevMode(TwitterConsumerLoader.scala:25)
    at com.lightbend.lagom.scaladsl.server.LagomApplicationLoader.load(LagomApplicationLoader.scala:54)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1$$anonfun$apply$1$$anonfun$2$$anonfun$3.apply(LagomReloadableDevServerStart.scala:151)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1$$anonfun$apply$1$$anonfun$2$$anonfun$3.apply(LagomReloadableDevServerStart.scala:148)
    at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1$$anonfun$apply$1$$anonfun$2.apply(LagomReloadableDevServerStart.scala:148)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1$$anonfun$apply$1$$anonfun$2.apply(LagomReloadableDevServerStart.scala:124)
    at scala.Option.map(Option.scala:146)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1$$anonfun$apply$1.apply(LagomReloadableDevServerStart.scala:124)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1$$anonfun$apply$1.apply(LagomReloadableDevServerStart.scala:122)
    at scala.util.Success.flatMap(Try.scala:231)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1.apply(LagomReloadableDevServerStart.scala:122)
    at play.core.server.LagomReloadableDevServerStart$$anonfun$mainDev$1$$anon$2$$anonfun$get$1.apply(LagomReloadableDevServerStart.scala:114)
    at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
    at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
    at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1402)
    at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
    at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
    at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
    at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

我的代码：

class TwitterConsumerLoader extends LagomApplicationLoader {

  override def load(context: LagomApplicationContext): LagomApplication =
    new TwitterConsumerApplication(context) {
      override def serviceLocator = NoServiceLocator
    }

  override def loadDevMode(context: LagomApplicationContext): LagomApplication =
    new TwitterConsumerApplication(context) with LagomDevModeComponents
}

abstract class TwitterConsumerApplication(context: LagomApplicationContext) extends LagomApplication(context)
  with CassandraPersistenceComponents with AhcWSComponents with LagomKafkaComponents {

  lazy val twitterService = serviceClient.implement[TwitterProducerService]

  override lazy val lagomServer = LagomServer.forServices()
  override lazy val jsonSerializerRegistry = TwitterSerializerRegistry

  persistentEntityRegistry.register(wire[TweetEntity])
  wire[TwitterProducerSubscriber]
}

如何在lagom中声明空服务 . 如果不可能，还有哪些替代方案？因为在将来可能需要在此模块中创建一些服务 . 我该如何解决这个问题？