query params question

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  queryParams: ['param1', 'param2'],
  param1: null,
  param2: null,
  actions:{
   change1(){
    this.set('param1', 'something'); 
   },
    change2(){
    this.set('param2', 'else'); 
   }
  }
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
    queryParams: {
    param1: {
      refreshModel: true,
      replace: true
    },
    param2: {
      refreshModel: true,
      replace: true
    }
  },
  model(params){
   if (!params.param1) {
     params.param1 = 'something 2'; 
   }
    if (!params.param2) {
     params.param2 = 'else 2'; 
   }
    return params;
  },
  setupController(controller, model){
    controller.set('param1', model.param1); 
    controller.set('param2', model.param2);
  }
  
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
param 1: {{param1}}
<button {{action 'change1'}}> change param 1 </button>
<br>
param 2: {{param2}}
<button {{action 'change2'}}> change param 2</button>

{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.7.0",
    "ember-data": "2.7.0",
    "ember-template-compiler": "2.7.0"
  },
  "addons": {}
}