Vaadin drop event is not fired when image with theme source is dropped to a target component

[Flaurite]

Description

See discussion in support forum: topic.

Steps to reproduce

1. Download demo project: demo.zip

2. Open VaadinDndScreen.

3. Try to move image with puppy. In the console you can see that Drop Event is occurred.

4. Try to move image with Jmix icon. No Drop Event is fired.

Technical notes

The problem does not occurs if we use URL source.

In the client-side in DropTargetExtensionConnector class in onDrop() method there is a check that does not apply Files type. It seems with new browser versions they start to add Files type to dragged image from ThemeResource, StreamResource and probably ClassPathResource and RelativePathResource (does not check).

[Flaurite]

FireFox fixed the issue in: https://bugzilla.mozilla.org/show_bug.cgi?id=1812611
Chrome still does not fire drop event for theme and stream resources.