Loading key to KeyStore fails on Android Oreo

getClass.getResourceAsStream("/app/subfolder1/keystore")
getClass.getResourceAsStream("keystore")

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

webView.setDownloadListener(new DownloadListener() {

        @Override

        public void onDownloadStart(String url, String userAgent,
                                    String contentDisposition, String mimetype,
                                    long contentLength) {
            DownloadManager.Request request = new DownloadManager.Request(
                    Uri.parse(url));
            if(Build.VERSION.SDK_INT <= 26 ){
                request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, URLUtil.guessFileName(url, contentDisposition, mimetype));
            }
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); //Notify client once download is completed!

            DownloadManager dm = (DownloadManager) getActivity().getSystemService(Context.DOWNLOAD_SERVICE);
            dm.enqueue(request);
            Toast.makeText(getActivity().getApplicationContext(), "Downloading File", //To notify the Client that the file is being downloaded
                    Toast.LENGTH_LONG).show();


        }



    });