code: private String encodeFileName(String fileName) {
  
  		String result = Normalizer.normalize(fileName, Normalizer.Form.NFD).replaceAll("\\s+", "-")
  				.replaceAll("[^A-Za-z0-9_\\-\\.]", "");
  		if (result.isEmpty()) {
  			result = "report";
  		}
  		return result;
  	}
docs: All characters different from a standard set are deleted