apollo-core/src/main/java/com/ctrip/framework/apollo/core/dto/ApolloNotificationMessages.java/ApolloNotificationMessages/mergeFrom
class ApolloNotificationMessages:  public void mergeFrom(ApolloNotificationMessages source) {
    if (source == null) {
      return;
    }

    for (Map.Entry<String, Long> entry : source.getDetails().entrySet()) {
      //to make sure the notification id always grows bigger
      if (this.has(entry.getKey()) &&
          this.get(entry.getKey()) >= entry.getValue()) {
        continue;
      }
      this.put(entry.getKey(), entry.getValue());
    }
  }