import mx.collections.ArrayCollection;
[Bindable]
private var employeeAC:ArrayCollection = new ArrayCollection();
private function initData():void
{
employeeAC.source = [{department:"Shipping",
children: [
{firstname:"A", lastname:"B"},
{firstname:"C", lastname:"D"}]},
{department:"E",
children: [
{firstname:"F", lastname:"G"},
{firstname:"H", lastname:"I"}]}
];
}