/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/ is in plasma-sdk 5.8.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/AppletConfiguration.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/ConfigCategoryDelegate.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/ConfigurationContainmentActions.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/ConfigurationContainmentAppearance.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/ConfigurationKcmPage.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/ConfigurationShortcuts.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/ContainmentConfiguration.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/MouseEventInputButton.qml
/usr/share/plasma/shells/org.kde.plasma.plasmoidviewershell/contents/configuration/PanelConfiguration.qml