/usr/include/msgpack/adaptor/ is in libmsgpack-dev 2.1.5-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/msgpack/adaptor/adaptor_base.hpp
/usr/include/msgpack/adaptor/adaptor_base_decl.hpp
/usr/include/msgpack/adaptor/array_ref.hpp
/usr/include/msgpack/adaptor/array_ref_decl.hpp
/usr/include/msgpack/adaptor/bool.hpp
/usr/include/msgpack/adaptor/boost/
/usr/include/msgpack/adaptor/boost/fusion.hpp
/usr/include/msgpack/adaptor/boost/msgpack_variant.hpp
/usr/include/msgpack/adaptor/boost/msgpack_variant_decl.hpp
/usr/include/msgpack/adaptor/boost/optional.hpp
/usr/include/msgpack/adaptor/boost/string_ref.hpp
/usr/include/msgpack/adaptor/boost/string_view.hpp
/usr/include/msgpack/adaptor/carray.hpp
/usr/include/msgpack/adaptor/char_ptr.hpp
/usr/include/msgpack/adaptor/check_container_size.hpp
/usr/include/msgpack/adaptor/check_container_size_decl.hpp
/usr/include/msgpack/adaptor/cpp11/
/usr/include/msgpack/adaptor/cpp11/array.hpp
/usr/include/msgpack/adaptor/cpp11/array_char.hpp
/usr/include/msgpack/adaptor/cpp11/array_unsigned_char.hpp
/usr/include/msgpack/adaptor/cpp11/forward_list.hpp
/usr/include/msgpack/adaptor/cpp11/reference_wrapper.hpp
/usr/include/msgpack/adaptor/cpp11/shared_ptr.hpp
/usr/include/msgpack/adaptor/cpp11/tuple.hpp
/usr/include/msgpack/adaptor/cpp11/unique_ptr.hpp
/usr/include/msgpack/adaptor/cpp11/unordered_map.hpp
/usr/include/msgpack/adaptor/cpp11/unordered_set.hpp
/usr/include/msgpack/adaptor/cpp17/
/usr/include/msgpack/adaptor/cpp17/optional.hpp
/usr/include/msgpack/adaptor/cpp17/string_view.hpp
/usr/include/msgpack/adaptor/define.hpp
/usr/include/msgpack/adaptor/define_decl.hpp
/usr/include/msgpack/adaptor/deque.hpp
/usr/include/msgpack/adaptor/ext.hpp
/usr/include/msgpack/adaptor/ext_decl.hpp
/usr/include/msgpack/adaptor/fixint.hpp
/usr/include/msgpack/adaptor/fixint_decl.hpp
/usr/include/msgpack/adaptor/float.hpp
/usr/include/msgpack/adaptor/int.hpp
/usr/include/msgpack/adaptor/int_decl.hpp
/usr/include/msgpack/adaptor/list.hpp
/usr/include/msgpack/adaptor/map.hpp
/usr/include/msgpack/adaptor/map_decl.hpp
/usr/include/msgpack/adaptor/msgpack_tuple.hpp
/usr/include/msgpack/adaptor/msgpack_tuple_decl.hpp
/usr/include/msgpack/adaptor/nil.hpp
/usr/include/msgpack/adaptor/nil_decl.hpp
/usr/include/msgpack/adaptor/pair.hpp
/usr/include/msgpack/adaptor/raw.hpp
/usr/include/msgpack/adaptor/raw_decl.hpp
/usr/include/msgpack/adaptor/set.hpp
/usr/include/msgpack/adaptor/size_equal_only.hpp
/usr/include/msgpack/adaptor/size_equal_only_decl.hpp
/usr/include/msgpack/adaptor/string.hpp
/usr/include/msgpack/adaptor/tr1/
/usr/include/msgpack/adaptor/tr1/unordered_map.hpp
/usr/include/msgpack/adaptor/tr1/unordered_set.hpp
/usr/include/msgpack/adaptor/v4raw.hpp
/usr/include/msgpack/adaptor/v4raw_decl.hpp
/usr/include/msgpack/adaptor/vector.hpp
/usr/include/msgpack/adaptor/vector_bool.hpp
/usr/include/msgpack/adaptor/vector_char.hpp
/usr/include/msgpack/adaptor/vector_unsigned_char.hpp