code: public void updateMetricFromRPC(Object value) {
          if (value == null) {
              incr();
          } else if (value instanceof Long) {
              incrBy((Long) value);
          } else {
              throw new RuntimeException("CountShellMetric updateMetricFromRPC params should be null or Long");
          }
      }
docs: *
  @param value should be null or long if value is null, it will call incr()
  if value is long, it will call incrBy((long)params)