apollo-client/src/main/java/com/ctrip/framework/apollo/model/ConfigFileChangeEvent.java/ConfigFileChangeEvent/ConfigFileChangeEvent
class ConfigFileChangeEvent:  public ConfigFileChangeEvent(String namespace, String oldValue, String newValue,
      PropertyChangeType changeType) {
    this.namespace = namespace;
    this.oldValue = oldValue;
    this.newValue = newValue;
    this.changeType = changeType;
  }