The release notes for GS2017 CU11 include
New functionality – Add custom fields to a project: It is now possible to provide additional information through custom fields to a project during project creation. The custom fields can also be used through the SDL Trados GroupShare API.
Where can I find this? The Swagger documentation for GS makes no mention of it. I'm also unable to find this functionality in GroupShareKit.
So how do I add custom fields to a project?