/usr/share/applications/unity-appearance-panel.desktop is in unity-control-center 15.04.0+18.04.20180216-0ubuntu1.
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 7 8 9 10 11 12 13 14 | [Desktop Entry]
Name=Appearance
Comment=Change the background and the theme
Exec=unity-control-center appearance
Icon=preferences-desktop-wallpaper
Terminal=false
Type=Application
StartupNotify=true
Categories=GNOME;GTK;Settings;DesktopSettings;X-Unity-Settings-Panel;X-GNOME-PersonalSettings
OnlyShowIn=Unity7;
X-Unity-Settings-Panel=appearance
# Translators: those are keywords for the appearance control-center panel
Keywords=Wallpaper;Background;Screen;Desktop;Theme;Appearance;Launcher;Unity;Menus;
X-Ubuntu-Gettext-Domain=unity-control-center
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