When converting a QIcon to a vector of images to D-Bus, the list of
available sizes is used to extract the pixmaps of the icon. In case
the engine of the icon advertizes no sizes, then no pixmaps are sent:
this is the case of the SVG icon engine shipped with QtSvg, so creating
a QIcon from an SVG file means nothing is sent for it.

As solution, use a list of few well-known sizes in case no size is
available: this way there is the possibility to have some pixmaps for
that icon.

• create a KStatusNotifierItem
• create a QIcon from a SVG file
• set that QIcon as pixmap for the KStatusNotifierItem, e.g. using setIconByPixmap

Without this change, no icon is shown in the Plasma tray.