/usr/include/KF5/KConfigCore/ is in libkf5config-dev 5.44.0-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/KConfigCore/ConversionCheck
/usr/include/KF5/KConfigCore/KAuthorized
/usr/include/KF5/KConfigCore/KConfig
/usr/include/KF5/KConfigCore/KConfigBase
/usr/include/KF5/KConfigCore/KConfigGroup
/usr/include/KF5/KConfigCore/KCoreConfigSkeleton
/usr/include/KF5/KConfigCore/KDesktopFile
/usr/include/KF5/KConfigCore/KEMailSettings
/usr/include/KF5/KConfigCore/KSharedConfig
/usr/include/KF5/KConfigCore/conversioncheck.h
/usr/include/KF5/KConfigCore/kauthorized.h
/usr/include/KF5/KConfigCore/kconfig.h
/usr/include/KF5/KConfigCore/kconfigbase.h
/usr/include/KF5/KConfigCore/kconfigcore_export.h
/usr/include/KF5/KConfigCore/kconfiggroup.h
/usr/include/KF5/KConfigCore/kcoreconfigskeleton.h
/usr/include/KF5/KConfigCore/kdesktopfile.h
/usr/include/KF5/KConfigCore/kemailsettings.h
/usr/include/KF5/KConfigCore/ksharedconfig.h