/usr/include/ignition/ is in libignition-transport4-dev 4.0.0+dfsg-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ignition/transport4/
/usr/include/ignition/transport4/ignition/
/usr/include/ignition/transport4/ignition/transport/
/usr/include/ignition/transport4/ignition/transport.hh
/usr/include/ignition/transport4/ignition/transport/AdvertiseOptions.hh
/usr/include/ignition/transport4/ignition/transport/Discovery.hh
/usr/include/ignition/transport4/ignition/transport/Export.hh
/usr/include/ignition/transport4/ignition/transport/HandlerStorage.hh
/usr/include/ignition/transport4/ignition/transport/Helpers.hh
/usr/include/ignition/transport4/ignition/transport/MessageInfo.hh
/usr/include/ignition/transport4/ignition/transport/NetUtils.hh
/usr/include/ignition/transport4/ignition/transport/Node.hh
/usr/include/ignition/transport4/ignition/transport/NodeOptions.hh
/usr/include/ignition/transport4/ignition/transport/NodeShared.hh
/usr/include/ignition/transport4/ignition/transport/Packet.hh
/usr/include/ignition/transport4/ignition/transport/Publisher.hh
/usr/include/ignition/transport4/ignition/transport/RepHandler.hh
/usr/include/ignition/transport4/ignition/transport/ReqHandler.hh
/usr/include/ignition/transport4/ignition/transport/SubscribeOptions.hh
/usr/include/ignition/transport4/ignition/transport/SubscriptionHandler.hh
/usr/include/ignition/transport4/ignition/transport/TopicStorage.hh
/usr/include/ignition/transport4/ignition/transport/TopicUtils.hh
/usr/include/ignition/transport4/ignition/transport/TransportTypes.hh
/usr/include/ignition/transport4/ignition/transport/Uuid.hh
/usr/include/ignition/transport4/ignition/transport/config.hh
/usr/include/ignition/transport4/ignition/transport/detail/
/usr/include/ignition/transport4/ignition/transport/detail/Export.hh
/usr/include/ignition/transport4/ignition/transport/ign.hh