code: public static boolean isDao(String groupName) {
          try {
              return GroupRouter.singleton.newestDefinition(groupName).isDao();
          } catch (GroupUndefinedException e) {
              throw new RuntimeException("Call GroupJudge.defined() first.", e);
          }
      }
docs: Judge whether the specified group is a dao group.
  
  @param groupName the specified group name.
  @return true if this group's dao property value is true, other wise flase.