title: scala play reads parse nested json
body: <p>I'm using <code>implicit val reads</code> to map Json like:</p>
  
  <pre><code>{
     "id": 1
     "friends": [
      {
        "id": 1,
        "since": ...
      },
      {
        "id": 2,
        "since": ...
      },
      {
        "id": 3,
        "since": ...
      }
    ]
  }
  </code></pre>
  
  <p>to a case class </p>
  
  <pre><code>case class Response(id: Long, friend_ids: Seq[Long])
  </code></pre>
  
  <p>I can only make it work with an intermediate class that reflects the JSON <code>friends</code> structure. But I never use it in my app. Is there a way to write a <code>Reads[Response]</code> object so that my Response class would map directly to the JSON given?</p>