[REG 5.14 -> 5.14.2, 5.15] QMetaType::registerConverter seems to be broken

Code that works with all versions from Qt [5.6.5.14] stopped working with Qt 5.15.

The situation, where I noticed the incompatibility can be seen in one of the qskinny example: https://github.com/uwerat/qskinny. If you like to debug your code you can download and run the layouts example. The background of the "Grid Layout" page is supposed to be white.

The problem is about the classes QskGradient/QskGradientStop:
https://github.com/uwerat/qskinny/blob/master/src/common/QskGradient.h

They are exposed to QML using QMetaType::registerConverter. The code can be found here: https://github.com/uwerat/qskinny/blob/master/qmlexport/QskQml.cpp

In QskControl.h ( https://github.com/uwerat/qskinny/blob/master/src/controls/QskControl.h ) you find this:

Q_PROPERTY( QskGradient background ... )

and finally in https://github.com/uwerat/qskinny/blob/master/examples/layouts/layouts.qml it is used like this:

GridBox
{
background
{
stops: [

,

,
]
}

....
}