/usr/include/ is in libkf5messagecore-dev 4:16.04.3-3~deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/
/usr/include/KF5/MessageCore/
/usr/include/KF5/MessageCore/AttachmentCompressJob
/usr/include/KF5/MessageCore/AttachmentFromFolderJob
/usr/include/KF5/MessageCore/AttachmentFromMimeContentJob
/usr/include/KF5/MessageCore/AttachmentFromUrlBaseJob
/usr/include/KF5/MessageCore/AttachmentFromUrlJob
/usr/include/KF5/MessageCore/AttachmentFromUrlUtils
/usr/include/KF5/MessageCore/AttachmentLoadJob
/usr/include/KF5/MessageCore/AttachmentPart
/usr/include/KF5/MessageCore/AttachmentPropertiesDialog
/usr/include/KF5/MessageCore/AttachmentUpdateJob
/usr/include/KF5/MessageCore/ImageCollector
/usr/include/KF5/MessageCore/MailingList
/usr/include/KF5/MessageCore/MessageCoreSettings
/usr/include/KF5/MessageCore/MessageCoreUtil
/usr/include/KF5/MessageCore/MessageHelpers
/usr/include/KF5/MessageCore/NodeHelper
/usr/include/KF5/MessageCore/StringUtil
/usr/include/KF5/messagecore/
/usr/include/KF5/messagecore/attachmentcompressjob.h
/usr/include/KF5/messagecore/attachmentfromfolderjob.h
/usr/include/KF5/messagecore/attachmentfrommimecontentjob.h
/usr/include/KF5/messagecore/attachmentfromurlbasejob.h
/usr/include/KF5/messagecore/attachmentfromurljob.h
/usr/include/KF5/messagecore/attachmentfromurlutils.h
/usr/include/KF5/messagecore/attachmentloadjob.h
/usr/include/KF5/messagecore/attachmentpart.h
/usr/include/KF5/messagecore/attachmentpropertiesdialog.h
/usr/include/KF5/messagecore/attachmentupdatejob.h
/usr/include/KF5/messagecore/globalsettings_messagecore.h
/usr/include/KF5/messagecore/imagecollector.h
/usr/include/KF5/messagecore/mailinglist.h
/usr/include/KF5/messagecore/messagecore_export.h
/usr/include/KF5/messagecore/messagecoresettings.h
/usr/include/KF5/messagecore/messagecoreutil.h
/usr/include/KF5/messagecore/messagehelpers.h
/usr/include/KF5/messagecore/nodehelper.h
/usr/include/KF5/messagecore/stringutil.h
/usr/include/KF5/messagecore_version.h