get json in play-framwork

I want to get a json string with my play-framework application() from a angularJS application.

This is what I actually send:

{"in":[
       {"id":4,"ip":"192.168.0.20","pinSysNo":4,"pinSysName":"pg6","folderName":"gpio4_pg6","alias":"d","direction":"digital_in"},
       {"id":3,"ip":"192.168.0.20","pinSysNo":3,"pinSysName":"pb18","folderName":"gpio3_pb18","alias":"c","direction":"digital_out"}
      ],
 "out":[
       {"id":1,"ip":"192.168.0.20","pinSysNo":1,"pinSysName":"pg3","folderName":"gpio1_pg3","alias":"a","direction":"digital_in"},
       {"id":2,"ip":"192.168.0.20","pinSysNo":2,"pinSysName":"pb16","folderName":"gpio2_pb16","alias":"b","direction":"digital_in"}
            ]
}:""

I always get the status code 500(internal server error). May some in my routes are not correct? routes:

POST        /networkInsertJson          controllers.NetworkController.InsertJson()

May do I have a problem with the last 3 chars from the json string?

This is my Controller:

public static Result InsertJson(){
    ObjectNode result = Json.newObject();
    JsonNode json = request().body().asJson();
    org.json.simple.parser.JSONParser parser = new JSONParser();
    JSONObject o = new JSONObject();
    try{
        o = (JSONObject) parser.parse(json.asText());
    }catch (Exception e){

    }

    JSONArray ins = (JSONArray) o.get("in");
    JSONArray outs = (JSONArray) o.get("out");

    //I return the json back for testing
    result.put("in", ins.toJSONString());
    return ok(result);
}

Could you help me to find the mistake?

I found my own mistake in these line :

result.put("in", ins.toJSONString());

I tried to insert an array as the content of an json element.