Why is there no access to the children of QObjects in the scripting engine via QJSEngine?

Question

Qt

Good day to all!
We have a widget and want to make it, along with its child objects, available in the scripting engine. For example, the widget myWidget with the button myButton.
This is how it all works:

QScriptEngine engine;
QWidget *myWidget = new QWidget;
QScriptValue objectValue = engine.newQObject(myWidget);
engine.globalObject().setProperty("myWidget", objectValue);

myWidget.myButton.objectName = "Another name" // Ok

However, if you create a scripting engine through QJSEngine (instead of QScriptEngine), the myButton property of the myWidget object is not available. Why?