// operation, we fetch this info from storage, and refresh the cache as well.
func (store *IAMStoreSys) ListGroups(ctx context.Context) (res []string, err error) {
	cache := store.lock()
	defer store.unlock()

	if store.getUsersSysType() == MinIOUsersSysType {
		m := map[string]GroupInfo{}
		err = store.loadGroups(ctx, m)
		if err != nil {
			return
		}
		cache.iamGroupsMap = m