/usr/ is in libmongo-client-dev 0.1.8-3.1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/
/usr/include/mongo-client/
/usr/include/mongo-client/bson.h
/usr/include/mongo-client/mongo-client.h
/usr/include/mongo-client/mongo-sync-cursor.h
/usr/include/mongo-client/mongo-sync-pool.h
/usr/include/mongo-client/mongo-sync.h
/usr/include/mongo-client/mongo-utils.h
/usr/include/mongo-client/mongo-wire.h
/usr/include/mongo-client/mongo.h
/usr/include/mongo-client/sync-gridfs-chunk.h
/usr/include/mongo-client/sync-gridfs-stream.h
/usr/include/mongo-client/sync-gridfs.h
/usr/lib/
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/libmongo-client.a
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/libmongo-client.pc
/usr/share/
/usr/share/doc/
/usr/share/doc/libmongo-client-dev/
/usr/share/doc/libmongo-client-dev/copyright
/usr/lib/x86_64-linux-gnu/libmongo-client.so
/usr/share/doc/libmongo-client-dev/changelog.Debian.gz