apollo-core/src/main/java/com/ctrip/framework/apollo/core/dto/ApolloConfigNotification.java/ApolloConfigNotification/toString
class ApolloConfigNotification:  @Override
  public String toString() {
    return "ApolloConfigNotification{" +
        "namespaceName='" + namespaceName + '\'' +
        ", notificationId=" + notificationId +
        '}';
  }