Remove WallpaperPlugin
It was used to show the KNS dialog to download wallpaper plugins. But nowadays we can and should just use the QML components provided by KNewStuff directly.
All occurency in plasma-desktop, plasma-bigscreen and
plasma-nano have open MRs to port away from it (or just remove the import).
plasma-bigscreen!25 (merged)
plasma-nano!8 (merged)
plasma-desktop!281 (merged)
Considering this component is called shellprivate and patches like https://phabricator.kde.org/D26665 got accepted, I assume that removing components is okay.
@cholland I feel a bit bad, because you wrote this code. But then the QML components were not available^^