FindAll method listing child content instead of only root elements

I have a Web API returning to an Ember app the JSON above:

[
  {
    "id": 1,
    "title": "Test",
    "link": "index",
    "isActive": false,
    "children": [
      {
        "id": 4,
        "title": "Test 2",
        "link": "index",
        "isActive": false
      }
    ]
  },
  {
    "id": 2,
    "title": "Test 3",
    "link": "index",
    "isActive": false,
    "children": [
      {
        "id": 5,
        "title": "Test 4 ",
        "link": "index",
        "isActive": false
      }
    ]
  },
  {
    "id": 3,
    "title": "Test 5",
    "link": "index",
    "isActive": false,
    "children": [
      {
        "id": 6,
        "title": "Test 6",
        "link": "index",
        "isActive": false
      },
      {
        "id": 7,
        "title": "Test 7",
        "link": "index",
        "isActive": false
      }
    ]
  }
]

When I try to call "findAll" method in Ember, it is listing the children menus as they are in root:

model() {
      return this.get('store').findAll('menu').then(function(menus){
        menus.forEach(function (item, index, enumerable) {
          console.log(item.get('title'));
        });
      });
  }

Console result:

Test 2
Test 4
Test 6
Test 7
Test
Test 3
Test 5

I want to bring just the root elements: "Test", "Test 3" and "Test 5". The rest will be in children attribute of the corresponding parent. Here is my "menu.js"

import DS from 'ember-data';

export default DS.Model.extend({    
  title: DS.attr('string'),
  link: DS.attr('string'),
  isActive: DS.attr('boolean'),
  icon: DS.attr('string'),
  children: DS.hasMany('menu', { inverse: null })
});