code: @RequestMapping(value = "/{groupId}/users", method = RequestMethod.GET)
      public ResponseEntity<Set<User>> findUsersOfGroup(@PathVariable Integer groupId) {
  
          try {
              Set<User> groupUsersSet = this.service.getUsersOfGroup(groupId);
              return new ResponseEntity<Set<User>>(groupUsersSet, HttpStatus.OK);
          } catch (Exception e) {
              LOG.error("Error finding group with id " + groupId + ": "
                  + e.getMessage());
              return new ResponseEntity<Set<User>>(HttpStatus.NOT_FOUND);
          }
      }
docs: Get the users of a specific group.
  
  @param groupId
  @return