/usr/include/KF5/KDeclarative/ is in libkf5declarative-dev 5.18.0-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/KDeclarative/CalendarEvents/
/usr/include/KF5/KDeclarative/CalendarEvents/CalendarEventsPlugin
/usr/include/KF5/KDeclarative/KDeclarative/
/usr/include/KF5/KDeclarative/KDeclarative/ConfigPropertyMap
/usr/include/KF5/KDeclarative/KDeclarative/KDeclarative
/usr/include/KF5/KDeclarative/KDeclarative/QmlObject
/usr/include/KF5/KDeclarative/KDeclarative/QmlObjectSharedEngine
/usr/include/KF5/KDeclarative/KQuickAddons/
/usr/include/KF5/KDeclarative/KQuickAddons/ConfigModule
/usr/include/KF5/KDeclarative/KQuickAddons/ImageTexturesCache
/usr/include/KF5/KDeclarative/KQuickAddons/ManagedTextureNode
/usr/include/KF5/KDeclarative/KQuickAddons/QuickViewSharedEngine
/usr/include/KF5/KDeclarative/QuickAddons/
/usr/include/KF5/KDeclarative/QuickAddons/ImageTexturesCache
/usr/include/KF5/KDeclarative/QuickAddons/ManagedTextureNode
/usr/include/KF5/KDeclarative/calendarevents/
/usr/include/KF5/KDeclarative/calendarevents/calendarevents_export.h
/usr/include/KF5/KDeclarative/calendarevents/calendareventsplugin.h
/usr/include/KF5/KDeclarative/kdeclarative/
/usr/include/KF5/KDeclarative/kdeclarative/configpropertymap.h
/usr/include/KF5/KDeclarative/kdeclarative/kdeclarative.h
/usr/include/KF5/KDeclarative/kdeclarative/kdeclarative_export.h
/usr/include/KF5/KDeclarative/kdeclarative/qmlobject.h
/usr/include/KF5/KDeclarative/kdeclarative/qmlobjectsharedengine.h
/usr/include/KF5/KDeclarative/kquickaddons/
/usr/include/KF5/KDeclarative/kquickaddons/configmodule.h
/usr/include/KF5/KDeclarative/kquickaddons/imagetexturescache.h
/usr/include/KF5/KDeclarative/kquickaddons/managedtexturenode.h
/usr/include/KF5/KDeclarative/kquickaddons/quickaddons_export.h
/usr/include/KF5/KDeclarative/kquickaddons/quickviewsharedengine.h
/usr/include/KF5/KDeclarative/quickaddons/
/usr/include/KF5/KDeclarative/quickaddons/imagetexturescache.h
/usr/include/KF5/KDeclarative/quickaddons/managedtexturenode.h
/usr/include/KF5/KDeclarative/quickaddons/quickaddons_export.h