@Override
  public int hashCode() {
    return memberId.hashCode();
  }
The notification is something like this "For Member ID: <ID> [ <StatName> = <Value> .. ]"

@param defn {@link StatAlertDefinition}
@return String representation of this object based on {@link StatAlertDefinition}
geode-core/src/main/java/org/apache/geode/admin/jmx/internal/StatAlertNotification.java