Gitlab - Create a Group with default_branch_name as for Projects?

Hi everyone,
I need to configure a Gitlab instance with some scripts and in particular I need to set programmatically a default_branch_name at Group Level for a new Group that I create using API.

But, differently from the Project API, even if inside the UI under settings → Repository is it possible to change the default_branch_name on a Group, the same is not possible using the API.

Do you know if exists a workaround for that (also using the gitlab-rails console)?

In summary, I need to create a Group using the API and configuring the default branch name. In this way all the projects that will be created inherit this default branch name.

Thanks.

(Feature Request: Add default_branch property to Groups REST API (#442298) · Issues · GitLab.org / GitLab · GitLab)