docs: public static CmsRole valueOf(CmsGroup group) {
  
          // check groups for internal representing the roles
          if (group.isRole()) {
              CmsRole role = valueOfGroupName(group.getName());
              if (role != null) {
                  return role;
              }
          }
          // check virtual groups mapping a role
          if (group.isVirtual()) {
              int index = (group.getFlags() & (I_CmsPrincipal.FLAG_CORE_LIMIT - 1));
              index = index / (I_CmsPrincipal.FLAG_GROUP_VIRTUAL * 2);
              CmsRole role = getSystemRoles().get(index);
              return role.forOrgUnit(group.getOuFqn());
          }
          return null;
      }