code: @Override
      public String fetchStatus(MonitoredInstance instance) {
          final UsernamePasswordCredentials credentials = StringUtils.isEmpty(instance.getUsername()) ? null :
                  new UsernamePasswordCredentials(instance.getUsername(), instance.getPassword());
          try {
              final HttpResponse response = HttpHelper.getHttpResponse(instance.getLocation(), credentials);
              final String content = HttpHelper.getResponseContent(response);
              if (HttpHelper.isScOk(response)) {
                  return content;
              } else {
                  LOGGER.warn("Response status code is not 200! Apache location = "
                          + instance.getLocation() + ", response=" + content);
              }
          } catch (IOException e) {
              LOGGER.warn("Failed to fetch content of URL ["+ instance.getLocation()+"].", e);
          }
          return null;
      }
docs: Fetch current status for the instance via HTTP(s).
  @param instance {@link MonitoredInstance} to fetch status from.
  @return retrieved status if server responded with response code 200,
  or null otherwise(another response code or in case of {@link IOException}).