docs: public static PrivateKey readPrivateKey(final File root, final String directory,
  		final String fileName) throws NoSuchAlgorithmException, InvalidKeySpecException,
  		NoSuchProviderException, IOException
  	{
  
  		final File privatekeyDir = new File(root, directory);
  		final File privatekeyFile = new File(privatekeyDir, fileName);
  
  		final PrivateKey privateKey = PrivateKeyReader.readPrivateKey(privatekeyFile);
  		return privateKey;
  	}