/usr/include/lxqt/ is in liblxqt0-dev 0.12.0-5.
This file is owned by root:root, with mode 0o755.
..
/usr/include/lxqt/LXQt/
/usr/include/lxqt/LXQt/Application
/usr/include/lxqt/LXQt/AutostartEntry
/usr/include/lxqt/LXQt/ConfigDialog
/usr/include/lxqt/LXQt/GridLayout
/usr/include/lxqt/LXQt/HtmlDelegate
/usr/include/lxqt/LXQt/Notification
/usr/include/lxqt/LXQt/PageSelectWidget
/usr/include/lxqt/LXQt/PluginInfo
/usr/include/lxqt/LXQt/Power
/usr/include/lxqt/LXQt/PowerManager
/usr/include/lxqt/LXQt/ProgramFinder
/usr/include/lxqt/LXQt/RotatedWidget
/usr/include/lxqt/LXQt/ScreenSaver
/usr/include/lxqt/LXQt/Settings
/usr/include/lxqt/LXQt/SingleApplication
/usr/include/lxqt/LXQt/Translator
/usr/include/lxqt/LXQt/lxqtapplication.h
/usr/include/lxqt/LXQt/lxqtautostartentry.h
/usr/include/lxqt/LXQt/lxqtconfigdialog.h
/usr/include/lxqt/LXQt/lxqtglobals.h
/usr/include/lxqt/LXQt/lxqtgridlayout.h
/usr/include/lxqt/LXQt/lxqthtmldelegate.h
/usr/include/lxqt/LXQt/lxqtnotification.h
/usr/include/lxqt/LXQt/lxqtpageselectwidget.h
/usr/include/lxqt/LXQt/lxqtplugininfo.h
/usr/include/lxqt/LXQt/lxqtpower.h
/usr/include/lxqt/LXQt/lxqtpowermanager.h
/usr/include/lxqt/LXQt/lxqtprogramfinder.h
/usr/include/lxqt/LXQt/lxqtrotatedwidget.h
/usr/include/lxqt/LXQt/lxqtscreensaver.h
/usr/include/lxqt/LXQt/lxqtsettings.h
/usr/include/lxqt/LXQt/lxqtsingleapplication.h
/usr/include/lxqt/LXQt/lxqttranslator.h