<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=296883) </details> <!--IssueSummary end--> <!-- This template is a great use for issues that are feature::additions or technical tasks for larger issues.--> ### Proposal Add existing database field of `custom_project_templates_group_id` to API endpoint for `/groups/:id/update` ### Use Case When trying to automate a Group `Custom project templates` selection of a sub-group, this is only available in the Web UI and is not in the API. I expect to find it in the Update group API endpoint, but only has `file_template_project_id` for the repository import rather than group of multiple projects. #### Screenshots  #### Existing Documentation https://docs.gitlab.com/ee/api/groups.html#update-group