XKB Common is a library for handling keyboard mapping and descriptions along with related tasks like parsing the descriptions, etc. The xkbcommon library is used by Wayland for handling keyboard mapping and is also used by KMSCON, GTK+, Qt, Clutter, and other open-source projects. More xkbcommon details for those interested can be found in its GitHub repository. This keyboard-related library is largely developed by well known X.Org developer Daniel Stone.
With Revision 593 to the Mir repository on Tuesday, Canonical's display server for Ubuntu Linux is now also using xkbcommon for key mapping. It's not a huge surprise that Mir is using xkbcommon for key mapping considering it's already widely used by other open-source projects, key mapping isn't hugely exciting, and XKB Common is released under the MIT/X11 license.
At least this library now being used by Mir is clear and Canonical isn't doing anything crazy like they did with Jolla's work.