Loading bar with scene files payload

Phaser 3
1

Hi,
Simple loading bar use load image after on progress, on fileprogress, and on complete :

this.load.on('progress', this.onProgress, this);
this.load.on('fileprogress', this.onFileProgress, this);
this.load.on('complete', this.onComplete, this);
this.load.image('aqua_ball');

https://phaser.io/examples/v3/view/loader/game-load-config

But, when we use scene files payload, how we can get callback for progress, fileprogress, and complete to build loading bar same like the example above?

const bootScene = new Phaser.Class({

    Extends: Phaser.Scene,

    initialize:

    function bootScene ()
    {
        Phaser.Scene.call(this, { key: 'boot', 
            pack: {
                files: [
                    { type: 'image', key: 'aqua_ball', url: 'aqua_ball.png' },
                ]
            }
    	});
    },
    init: function (data) {
    	...
    },
    preload: function () {

    	// progress loading bar?
    	this.load.on('progress', this.onProgress, this);
        this.load.on('fileprogress', this.onFileProgress, this);
        this.load.on('complete', this.onComplete, this);

    },
    create: function (data) {
    	...
    },
});