/usr/include/KF5/ is in libkf5mailimporter-dev 4:17.12.3-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/MailImporter/
/usr/include/KF5/MailImporter/FilterBalsa
/usr/include/KF5/MailImporter/FilterClawsMail
/usr/include/KF5/MailImporter/FilterEvolution
/usr/include/KF5/MailImporter/FilterEvolution_v2
/usr/include/KF5/MailImporter/FilterEvolution_v3
/usr/include/KF5/MailImporter/FilterIcedove
/usr/include/KF5/MailImporter/FilterImporterBase
/usr/include/KF5/MailImporter/FilterInfo
/usr/include/KF5/MailImporter/FilterInfoGui
/usr/include/KF5/MailImporter/FilterKMailArchive
/usr/include/KF5/MailImporter/FilterKMail_maildir
/usr/include/KF5/MailImporter/FilterLNotes
/usr/include/KF5/MailImporter/FilterMBox
/usr/include/KF5/MailImporter/FilterMailApp
/usr/include/KF5/MailImporter/FilterMailmanGzip
/usr/include/KF5/MailImporter/FilterOE
/usr/include/KF5/MailImporter/FilterOpera
/usr/include/KF5/MailImporter/FilterPMail
/usr/include/KF5/MailImporter/FilterPlain
/usr/include/KF5/MailImporter/FilterSeaMonkey
/usr/include/KF5/MailImporter/FilterSylpheed
/usr/include/KF5/MailImporter/FilterTheBat
/usr/include/KF5/MailImporter/FilterThunderbird
/usr/include/KF5/MailImporter/Filters
/usr/include/KF5/MailImporter/ImportMailsWidget
/usr/include/KF5/MailImporter/MailImporter_Utils
/usr/include/KF5/MailImporter/MessageStatus
/usr/include/KF5/MailImporter/OtherMailerUtil
/usr/include/KF5/MailImporterAkonadi/
/usr/include/KF5/MailImporterAkonadi/FilterImporterAkonadi
/usr/include/KF5/mailimporter/
/usr/include/KF5/mailimporter/filterbalsa.h
/usr/include/KF5/mailimporter/filterclawsmail.h
/usr/include/KF5/mailimporter/filterevolution.h
/usr/include/KF5/mailimporter/filterevolution_v2.h
/usr/include/KF5/mailimporter/filterevolution_v3.h
/usr/include/KF5/mailimporter/filtericedove.h
/usr/include/KF5/mailimporter/filterimporterbase.h
/usr/include/KF5/mailimporter/filterinfo.h
/usr/include/KF5/mailimporter/filterinfogui.h
/usr/include/KF5/mailimporter/filterkmail_maildir.h
/usr/include/KF5/mailimporter/filterkmailarchive.h
/usr/include/KF5/mailimporter/filterlnotes.h
/usr/include/KF5/mailimporter/filtermailapp.h
/usr/include/KF5/mailimporter/filtermailmangzip.h
/usr/include/KF5/mailimporter/filtermbox.h
/usr/include/KF5/mailimporter/filteroe.h
/usr/include/KF5/mailimporter/filteropera.h
/usr/include/KF5/mailimporter/filterplain.h
/usr/include/KF5/mailimporter/filterpmail.h
/usr/include/KF5/mailimporter/filters.h
/usr/include/KF5/mailimporter/filterseamonkey.h
/usr/include/KF5/mailimporter/filtersylpheed.h
/usr/include/KF5/mailimporter/filterthebat.h
/usr/include/KF5/mailimporter/filterthunderbird.h
/usr/include/KF5/mailimporter/importmailswidget.h
/usr/include/KF5/mailimporter/mailimporter_export.h
/usr/include/KF5/mailimporter/mailimporter_utils.h
/usr/include/KF5/mailimporter/messagestatus.h
/usr/include/KF5/mailimporter/othermailerutil.h
/usr/include/KF5/mailimporter_version.h
/usr/include/KF5/mailimporterakonadi/
/usr/include/KF5/mailimporterakonadi/filterimporterakonadi.h
/usr/include/KF5/mailimporterakonadi/mailimporterakonadi_export.h
/usr/include/KF5/mailimporterakonadi_version.h