/usr/include/KF5/Akonadi/Contact/ is in libkf5akonadicontact-dev 4:15.12.3-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/Akonadi/Contact/AbstractContactFormatter
/usr/include/KF5/Akonadi/Contact/AbstractContactGroupFormatter
/usr/include/KF5/Akonadi/Contact/ContactDefaultActions
/usr/include/KF5/Akonadi/Contact/ContactEditor
/usr/include/KF5/Akonadi/Contact/ContactEditorDialog
/usr/include/KF5/Akonadi/Contact/ContactEditorPagePlugin
/usr/include/KF5/Akonadi/Contact/ContactGroupEditor
/usr/include/KF5/Akonadi/Contact/ContactGroupEditorDialog
/usr/include/KF5/Akonadi/Contact/ContactGroupExpandJob
/usr/include/KF5/Akonadi/Contact/ContactGroupSearchJob
/usr/include/KF5/Akonadi/Contact/ContactGroupViewer
/usr/include/KF5/Akonadi/Contact/ContactGroupViewerDialog
/usr/include/KF5/Akonadi/Contact/ContactParts
/usr/include/KF5/Akonadi/Contact/ContactSearchJob
/usr/include/KF5/Akonadi/Contact/ContactViewer
/usr/include/KF5/Akonadi/Contact/ContactViewerDialog
/usr/include/KF5/Akonadi/Contact/ContactsFilterProxyModel
/usr/include/KF5/Akonadi/Contact/ContactsTreeModel
/usr/include/KF5/Akonadi/Contact/EmailAddressRequester
/usr/include/KF5/Akonadi/Contact/EmailAddressSelection
/usr/include/KF5/Akonadi/Contact/EmailAddressSelectionDialog
/usr/include/KF5/Akonadi/Contact/EmailAddressSelectionWidget
/usr/include/KF5/Akonadi/Contact/RecentContactsCollectionRequestJob
/usr/include/KF5/Akonadi/Contact/SelectAddressBookDialog
/usr/include/KF5/Akonadi/Contact/StandardContactActionManager
/usr/include/KF5/Akonadi/Contact/StandardContactFormatter
/usr/include/KF5/Akonadi/Contact/StandardContactGroupFormatter