@Override
    public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
      // if the alert was a selendroid one, this method will return true, otherwise false
      // and the alert should be propagated to the original WebChromeClient
      if (!selendroidWCC.onJsAlert(view, url, message, result)) {
        return WCC.onJsAlert(view, url, message, result);
      }
      return true;
    }
Unconventional way of adding a Javascript interface but the main reason why I took this way
is that it is working stable compared to the webview.addJavascriptInterface way.
selendroid-server/src/main/java/io/selendroid/server/model/SelendroidWebDriver.java