docs: protected void configureMetrics() {
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS, ESMetrics.class.getName());
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS + ".client.type", "jest");
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS + ".client.protocol", "${apiman.es.protocol}");
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS + ".client.host", "${apiman.es.host}");
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS + ".client.port", "${apiman.es.port}");
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS + ".client.username", "${apiman.es.username}");
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS + ".client.password", "${apiman.es.password}");
          setConfigProperty(GatewayConfigProperties.METRICS_CLASS + ".client.index", "apiman_metrics");
      }