/usr/include/KF5/KNewStuff3/ is in libkf5newstuff-dev 5.44.0-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/KNewStuff3/KNS3/
/usr/include/KF5/KNewStuff3/KNS3/Button
/usr/include/KF5/KNewStuff3/KNS3/DownloadDialog
/usr/include/KF5/KNewStuff3/KNS3/DownloadManager
/usr/include/KF5/KNewStuff3/KNS3/DownloadWidget
/usr/include/KF5/KNewStuff3/KNS3/Entry
/usr/include/KF5/KNewStuff3/KNS3/KMoreTools
/usr/include/KF5/KNewStuff3/KNS3/KMoreToolsMenuFactory
/usr/include/KF5/KNewStuff3/KNS3/KMoreToolsPresets
/usr/include/KF5/KNewStuff3/KNS3/UploadDialog
/usr/include/KF5/KNewStuff3/KNSCore/
/usr/include/KF5/KNewStuff3/KNSCore/Author
/usr/include/KF5/KNewStuff3/KNSCore/Cache
/usr/include/KF5/KNewStuff3/KNSCore/DownloadManager
/usr/include/KF5/KNewStuff3/KNSCore/Engine
/usr/include/KF5/KNewStuff3/KNSCore/EntryInternal
/usr/include/KF5/KNewStuff3/KNSCore/Installation
/usr/include/KF5/KNewStuff3/KNSCore/ItemsModel
/usr/include/KF5/KNewStuff3/KNSCore/Provider
/usr/include/KF5/KNewStuff3/KNSCore/Question
/usr/include/KF5/KNewStuff3/KNSCore/QuestionListener
/usr/include/KF5/KNewStuff3/KNSCore/QuestionManager
/usr/include/KF5/KNewStuff3/KNSCore/Security
/usr/include/KF5/KNewStuff3/KNSCore/XmlLoader
/usr/include/KF5/KNewStuff3/kns3/
/usr/include/KF5/KNewStuff3/kns3/button.h
/usr/include/KF5/KNewStuff3/kns3/downloaddialog.h
/usr/include/KF5/KNewStuff3/kns3/downloadmanager.h
/usr/include/KF5/KNewStuff3/kns3/downloadwidget.h
/usr/include/KF5/KNewStuff3/kns3/entry.h
/usr/include/KF5/KNewStuff3/kns3/kmoretools.h
/usr/include/KF5/KNewStuff3/kns3/kmoretoolsmenufactory.h
/usr/include/KF5/KNewStuff3/kns3/kmoretoolspresets.h
/usr/include/KF5/KNewStuff3/kns3/knewstuff_export.h
/usr/include/KF5/KNewStuff3/kns3/knewstuffaction.h
/usr/include/KF5/KNewStuff3/kns3/uploaddialog.h
/usr/include/KF5/KNewStuff3/knscore/
/usr/include/KF5/KNewStuff3/knscore/author.h
/usr/include/KF5/KNewStuff3/knscore/cache.h
/usr/include/KF5/KNewStuff3/knscore/downloadmanager.h
/usr/include/KF5/KNewStuff3/knscore/engine.h
/usr/include/KF5/KNewStuff3/knscore/entryinternal.h
/usr/include/KF5/KNewStuff3/knscore/installation.h
/usr/include/KF5/KNewStuff3/knscore/itemsmodel.h
/usr/include/KF5/KNewStuff3/knscore/knewstuffcore_export.h
/usr/include/KF5/KNewStuff3/knscore/provider.h
/usr/include/KF5/KNewStuff3/knscore/question.h
/usr/include/KF5/KNewStuff3/knscore/questionlistener.h
/usr/include/KF5/KNewStuff3/knscore/questionmanager.h
/usr/include/KF5/KNewStuff3/knscore/security.h
/usr/include/KF5/KNewStuff3/knscore/xmlloader.h