code: protected static void registerStatsdMetricObserver(List<MetricObserver> observers, String prefix, String host, String port) {
          // verify at least hostname is set, else cannot configure this observer
          if (null == host || host.trim().isEmpty()) {
              LOGGER.info("StatdsMetricObserver not configured, missing environment variable: {}", ENV_STATSD_HOSTNAME);
              return;
          }
  
          LOGGER.debug("{} environment variable is: {}", ENV_STATSD_PREFIX, prefix);
          LOGGER.debug("{} environment variable is: {}", ENV_STATSD_HOSTNAME, host);
          LOGGER.debug("{} environment variable is: {}", ENV_STATSD_PORT, port);
  
          int iport = -1;
          if (port != null && !port.isEmpty()) {
              try {
                  iport = Integer.valueOf(port);
              } catch (NumberFormatException e) {
                  iport = -1;
                  LOGGER.warn("Configured port is not an integer.  Falling back to default");
              }
          }
  
          if (iport < 0) {
              iport = 8125; //default statsd port
              LOGGER.debug("Using default port: " + port);
          }
  
          LOGGER.debug("StatsdMetricObserver prefix: " + prefix);
          LOGGER.debug("StatsdMetricObserver host: " + host);
          LOGGER.debug("StatsdMetricObserver port: " + iport);
  
          observers.add(new StatsdMetricObserver(prefix, host, iport));
      }
docs: If there is sufficient configuration, register a StatsD metric observer
  to publish metrics. Requires at a minimum a host. Optionally can set
  prefix as well as port. The prefix defaults to an empty string and port
  defaults to '8125'.