docs: def get_tenants(tenant_id=None):
      """Returns list of all project/tenant ids that may be relevant on CVX"""
      if tenant_id == '':
          return []
      session = db.get_reader_session()
      project_ids = set()
      with session.begin():
          for m in [models_v2.Network, models_v2.Port]:
              q = session.query(m.project_id).filter(m.project_id != '')
              if tenant_id:
                  q = q.filter(m.project_id == tenant_id)
              project_ids.update(pid[0] for pid in q.distinct())
      return [{'project_id': project_id} for project_id in project_ids]