code: @GET
    public Response getConfigurableUsers(@HeaderParam("Authorization") @DefaultValue("no token") String auth) throws Exception {
      if(!this.isAuth(auth)) {
        throw new Exception("Unauthorized!");
      }
      if( realm != null ) {
        List<String> usernames = new ArrayList<String>();
        usernames = realm.listUsers();
        return Response.ok(new Gson().toJson(usernames), MediaType.APPLICATION_JSON).build();
      }
      return Response.status(Status.NOT_FOUND).build();
    }
docs: Returns a list of users specific to this site only.
  
  @param auth
  @return
  @throws Exception