code: protected AggregatedHttpMessage newUnhealthyResponse(
              @SuppressWarnings("UnusedParameters") ServiceRequestContext ctx) {
  
          return AggregatedHttpMessage.of(HttpStatus.SERVICE_UNAVAILABLE, MediaType.PLAIN_TEXT_UTF_8, RES_NOT_OK);
      }
docs: Creates a new response which is sent when the {@link Server} is unhealthy.