/etc/xdg/kwineffect.knsrc is in kwin-common 4:5.5.5-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | [KNewStuff3]
ProvidersUrl=http://download.kde.org/ocs/providers.xml
Categories=KWin Effects
StandardResource=tmp
InstallationCommand=plasmapkg2 -t kwineffect -i %f
UninstallCommand=plasmapkg2 -t kwineffect -r %f
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