Get all projects (including subgroups) for a given namespace

What I would like to do is to get all projects that are in a namespace (in any sub group).

Given I have the following structure (I'm owner of all groups and projects):

• Group1
  • Subgroup1
    • Subsubgroup1
      • ProjectA
    • Subsubgroup2
      • ProjectB
    • SubsubgroupN
      • ProjectC
  • Subgroup2
    • Subsubgroup1
      • ProjectD
    • Subsubgroup2
      • ProjectE
    • SubsubgroupN
      • ProjectF
• Group2
  • Subgroup1
    • Subsubgroup1
      • ProjectG
    • Subsubgroup2
      • ProjectH
    • SubsubgroupN
      • ProjectI
  • Subgroup2
    • Subsubgroup1
      • ProjectJ
    • Subsubgroup2
      • ProjectK
    • SubsubgroupN
      • ProjectL

For a given request I only need all projects that are in Group1/Subgroup1. In this example that would be ProjectA, ProjectB and ProjectC.

Is this somehow possible?

I tried /api/v4/groups/Group1%2FSubgroup1/projects but that only returns a empty list.

I also tried /api/v4/projects/Group1%2FSubgroup1 but that only return 404 Project Not Found.

If this is not possible, I would like to add this feature request.

I first thought my question was related to the following issue (https://gitlab.com/gitlab-org/gitlab-ce/issues/23185) but after further reading I think there is a main difference. The main problem of my question seems to be that the API doesn't return projects of subgroups and subsubgroups and so on.