How to parse a class with List as a field using FlexJson JSONDeserializer?

Question

I want to parse a string to a class which has a List as a field and also another object. Here's the class:

Result result;
List<Param> params;

and the string:

{  
  "result":{  
    "isOk":true,
    "message":"OK"
  },
  "params":[  
    {  
      "id":123,
      "name":"ASD"
    },
    {  
      "id":987,
      "name":"QWE"
    }
  ]
}

Based on the question I tried to use .use() option but I only managed to get a HashMap. The documentation is not clear for me.

Edit: Now I've made some changes to figure this out and can't even get the hashmap...

Edit2: Okay, I got the hashmap but it's crazy.

I've managed to do:

HashMap<String, List<Params>> map = 
  new JSONDeserializer<HashMap<String, List<Params>>>()
        .use("null", List.class)
        .use("params", Params.class)
        .deserialize(json);

then I do:

List<Params> params = mapa.get("params");

but Param param = params.get(0); returns failed cast HashMap to Params...