code: @Override
  	public String parse(String argument) throws CommandLineException {
  
  		File file = new File(argument);
  
  		try {
  			Assert.isTrue(file.exists(), "File '" + file + "' does not exist");
  			Assert.isFalse(file.isDirectory(), "File '" + file + "' is a directory");
  			Assert.isTrue(file.canRead(), "File '" + file + "' cannot be read");
  		}
  		catch (IllegalArgumentException e) {
  			throw new CommandLineException(e.getMessage());
  		}
  
  		return file.getAbsolutePath();
  	}
docs: Expects file that is available and readable
  
  @param argument given argument in command line
  @return absolute file path
  
  @throws CommandLineException in case file name does not exists are can't be read