public boolean containsValue(final Object value) {
    return this._current.containsValue(value)
        || (this._parent != null && this._parent.containsValue(value));
  }
Check value in current Props then search in parent
dss-appconn/appconns/dss-eventchecker-appconn/src/main/java/com/webank/wedatasphere/dss/appconn/eventchecker/utils/Props.java