title: scala spray.json how to get Json Object
body: <p>If I try Http Get Response <code>{"ReturnValue":""}</code>,
  this Code make error.</p>
  
  <blockquote>
    <p>Caused by: spray.json.DeserializationException: Expected List as
    JsArray, but got {"ReturnValue":""}</p>
  </blockquote>
  
  <pre><code>import spray.httpx.SprayJsonSupport._
  import spray.json.DefaultJsonProtocol
  import spray.http._
  import spray.client.pipelining._
  import scala.concurrent.duration._
  import scala.concurrent.{ Await, Future }
  import akka.actor.ActorSystem
  import scala.concurrent.ExecutionContext.Implicits.global
  
  class ApiHelper extends DefaultJsonProtocol {
    case class Robot(name: String, color: Option[String], amountOfArms: Int)
  
    implicit val RobotFormat = jsonFormat3(Robot)
    def CallAPI(httpMethod: String, subURL: String): String = {
      val apiLocation = "~~~"
      val timeout = 5.seconds
  
      implicit val system = ActorSystem("robotClient")
      return httpMethod match {
        case "GET" =&gt;
          val pipeline: HttpRequest =&gt; Future[List[Robot]] = sendReceive ~&gt; unmarshal[List[Robot]]
          val f: Future[List[Robot]] = pipeline(Get(s"$apiLocation"+subURL))
          val robots = Await.result(f, timeout)
          println(s"Got the list of robots: $robots")
          return "hello"
      }
    }
  }
  </code></pre>
  
  <blockquote>
    <p>Caused by: spray.json.DeserializationException: Expected List as JsArray, but got {"ReturnValue":""}  at</p>
    
    <p>spray.json.package$.deserializationError(package.scala:23)    at
    spray.json.CollectionFormats$$anon$1.read(CollectionFormats.scala:29)
      at
    spray.json.CollectionFormats$$anon$1.read(CollectionFormats.scala:25)
      at
    spray.httpx.SprayJsonSupport$$anonfun$sprayJsonUnmarshaller$1.applyOrElse(SprayJsonSupport.scala:37)
      at
    spray.httpx.SprayJsonSupport$$anonfun$sprayJsonUnmarshaller$1.applyOrElse(SprayJsonSupport.scala:34)
      at
    scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:36)
      at
    spray.httpx.unmarshalling.Unmarshaller$$anon$1$$anonfun$unmarshal$1.apply(Unmarshaller.scala:29)
      at
    spray.httpx.unmarshalling.SimpleUnmarshaller.protect(SimpleUnmarshaller.scala:40)
      at
    spray.httpx.unmarshalling.Unmarshaller$$anon$1.unmarshal(Unmarshaller.scala:29)
      at
    spray.httpx.unmarshalling.SimpleUnmarshaller.apply(SimpleUnmarshaller.scala:29)
      at
    spray.httpx.unmarshalling.SimpleUnmarshaller.apply(SimpleUnmarshaller.scala:23)
      at
    spray.httpx.unmarshalling.UnmarshallerLifting$$anon$3.apply(UnmarshallerLifting.scala:35)
      at
    spray.httpx.unmarshalling.UnmarshallerLifting$$anon$3.apply(UnmarshallerLifting.scala:34)
      at
    spray.httpx.unmarshalling.UnmarshallerLifting$$anon$2.apply(UnmarshallerLifting.scala:30)
      at
    spray.httpx.unmarshalling.UnmarshallerLifting$$anon$2.apply(UnmarshallerLifting.scala:29)
      at
    spray.httpx.unmarshalling.package$PimpedHttpResponse.as(package.scala:51)
      at
    spray.httpx.ResponseTransformation$$anonfun$unmarshal$1.apply(ResponseTransformation.scala:33)
      ... 13 more</p>
  </blockquote>
  
  <p>Is there any way to get Json Object?</p>