code: private Response fail(String ticket, Reason reason)
      {
          try
          {
              // Generate an error response to indicate that
              // the authorization request failed.
              return getApiCaller().authorizationFail(ticket, reason).getResponse();
          }
          catch (WebApplicationException e)
          {
              return e.getResponse();
          }
      }
docs: Generate an error response to indicate that the authorization
  request failed. This method calls Authlete's {@code
  /api/auth/authorization/fail} API and generates a response that
  triggers redirection.
  </p>
  
  @param ticket
  A ticket that was issued by Authlete's {@code /api/auth/authorization} API.
  
  @param reason
  A reason of the failure of the authorization request.
  
  @return
  A response that should be returned to the client application.