/usr/include/KF5/KUnitConversion/ is in libkf5unitconversion-dev 5.28.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/KUnitConversion/KUnitConversion/
/usr/include/KF5/KUnitConversion/KUnitConversion/Converter
/usr/include/KF5/KUnitConversion/KUnitConversion/Unit
/usr/include/KF5/KUnitConversion/KUnitConversion/UnitCategory
/usr/include/KF5/KUnitConversion/KUnitConversion/Value
/usr/include/KF5/KUnitConversion/kunitconversion/
/usr/include/KF5/KUnitConversion/kunitconversion/converter.h
/usr/include/KF5/KUnitConversion/kunitconversion/kunitconversion_export.h
/usr/include/KF5/KUnitConversion/kunitconversion/unit.h
/usr/include/KF5/KUnitConversion/kunitconversion/unitcategory.h
/usr/include/KF5/KUnitConversion/kunitconversion/value.h