title: scala json4s how can i extract field by condition
body: <p>I've got json(for example): </p>
  
  <pre><code>{
    "name": "",
    "count": 2,
    "children": {
      "app_open": {
        "name": "app_open",
        "count": 1,
        "children": {
          "session_end": {
            "name": "session_end",
            "count": 1,
            "children": {}
          }
        }
      },
      "app_install": {
        "name": "app_install",
        "count": 2,
        "children": {
          "session_end": {
            "name": "session_end",
            "count": 2,
            "children": {}
          }
        }
      },
      "app_instal1l": {
        "name": "app_instal1l",
        "count": 3,
        "children": {
          "app_open": {
            "name": "app_open",
            "count": 3,
            "children": {
              "session_end": {
                "name": "session_end",
                "count": 3,
                "children": {}
              }
            }
          }
        }
      }
    }
  }
  </code></pre>
  
  <p>I need to extract all count where "name" = "app_open".</p>
  
  <p>And I trying do it with json4s library:</p>
  
  <pre><code>val name = jsonInput filterField {
             case JField("name", "app_open") =&gt; true
             case _ =&gt; false
           }
  println("name = " + URL)
  </code></pre>
  
  <p>And i suggest in output i'll have something with only "app_open", but i got:</p>
  
  <pre><code>name = List((name,JString(app_open)), (name,JString(session_end)), 
  (name,JString(app_open)), (name,JString(session_end)))
  </code></pre>
  
  <p>What i'm doing wrong here? 
  Thank you!</p>