code: public void setResponseURL(String responseURL) {
      String newURL = _substitutor.replace(responseURL);
      if (!_urlValidator.isValid(newURL)) {
        error("The RespondTo URL specified is invalid. Continuing with previous value.");
      } else {
        this._responseURL = newURL;
      }
    }
docs: Sets the respondTo URL for the client probes to use. If the URL is invalid
  it does nothing.
  
  @param responseURL URL for the client probes to use