NetworkAccessManagerFactory is not called for WebView content

I have A QuickWidget using a qml file that contains a WebView.

I want to have my own NetworkAccessManagerFactory to be able to control the caching behavior of the webview. So i have created my own QQmlNetworkAccessManagerFactory inherited class as mentionned in the docs (http://doc.qt.io/qt-5/qqmlnetworkaccessmanagerfactory.html).

If i have an image like in the sample which source is pointing to an url, then the NetworkAccessManagerFactory::create() method is called. but if i have only the webview it is not.

Therefore, the cache mechanism of the qml WebView cannot be controlled.

I have attached a small testcase showing the issue, the NetAccessManagerFactory::create() is never being called.