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