title: Guice Multibinder Doesn't Work with Play Framework
body: <p>Using Play 2.5.8 with Scala 2.11.8.</p>
  
  <p>I've a trait <code>RequestMatcher</code> and multiple implementations of it. I'd like to have a <code>Seq[RequestMatcher]</code> injected in my service. My module looks like the following:</p>
  
  <pre><code>class FeignModule(environment: Environment, configuration: Configuration) extends AbstractModule with AkkaGuiceSupport {
    def configure() = {
      val requestMatcherBinder = Multibinder.newSetBinder(binder(), classOf[RequestMatcher])
      // TODO: Allow for user specified matchers
      requestMatcherBinder.addBinding().to(classOf[DefaultPathMatcher])
      requestMatcherBinder.addBinding().to(classOf[DefaultMethodMatcher])
      requestMatcherBinder.addBinding().to(classOf[DefaultQueriesMatcher])
      requestMatcherBinder.addBinding().to(classOf[DefaultHeadersMatcher])
      requestMatcherBinder.addBinding().to(classOf[DefaultBodyMatcher])
  
      // TODO: Allow for user specified actors
      bindActor[DefaultRecordingService]("recordingService")
    }
  }
  </code></pre>
  
  <p>The injection target is as follows:</p>
  
  <pre><code>@javax.inject.Singleton
  class FeignService @Inject()(@Named("recordingService") val recordingService: ActorRef,
                               val feignProperties: FeignProperties,
                               val matchers: Seq[RequestMatcher])
                              (implicit val ec: ExecutionContext) {
  }
  </code></pre>
  
  <p>But</p>
  
  <blockquote>
    <p>play.api.UnexpectedException: Unexpected exception[ProvisionException:
    Unable to provision, see the following errors:</p>
    
    <p>1) No implementation for
    scala.collection.Seq was
    bound.   while locating
    scala.collection.Seq
        for the 3rd parameter of service.FeignService.(FeignService.scala:19)</p>
  </blockquote>
  
  <p>I know the module is read by Play because the Actor (1st parameter to <code>FeignService</code>) is injected just fine. I have the <code>guice-multibindings</code> jar on classpath too.</p>
  
  <p>What's wrong?</p>