/usr/include/ags/object/ is in libags-dev 1.4.24-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ags/object/ags_applicable.h
/usr/include/ags/object/ags_application_context.h
/usr/include/ags/object/ags_async_queue.h
/usr/include/ags/object/ags_concurrent_tree.h
/usr/include/ags/object/ags_config.h
/usr/include/ags/object/ags_connectable.h
/usr/include/ags/object/ags_connection.h
/usr/include/ags/object/ags_connection_manager.h
/usr/include/ags/object/ags_countable.h
/usr/include/ags/object/ags_distributed_manager.h
/usr/include/ags/object/ags_dynamic_connectable.h
/usr/include/ags/object/ags_macros.h
/usr/include/ags/object/ags_main_loop.h
/usr/include/ags/object/ags_marshal.h
/usr/include/ags/object/ags_mutable.h
/usr/include/ags/object/ags_packable.h
/usr/include/ags/object/ags_plugin.h
/usr/include/ags/object/ags_portlet.h
/usr/include/ags/object/ags_seekable.h
/usr/include/ags/object/ags_sequencer.h
/usr/include/ags/object/ags_soundcard.h
/usr/include/ags/object/ags_tactable.h
/usr/include/ags/object/ags_tree_iterator.h