ExtJs 4.2: 'id' of Controller

Question

I have set the 'id' config of controller like

Ext.define('App.controller.popUpController', {
    extend: 'Ext.app.Controller',

    /**
     * @cfg {String} view
     * View for which popUpController will act as a controller
     */
    view: [
        'PopUpWindow'
    ],

    id:'testController'
})

But when I am trying to retrieve id of controller to pass it to

Ext.app.EventBus.unlisten(App.app.getController('popUpController').id)

It is returning name of controller: 'popUpController' not the id: 'testController'. Although I am achieving my goal to unlisten all event handlers related to my controller but my question is why the 'id' property is returning me name and not the given id of the controller?