code: public Set<String> getBundleCodes(Locale locale,String...basenames){
  		List<String> validBaseNames = getValidBasenames(basenames);
  		
  		Set<String> codes = new HashSet<>();
  		for(String basename: validBaseNames){
  			List<Pair<String, Resource>> filenamesAndResources = calculateAllFilenames(basename,locale);
  			for (Pair<String, Resource> filenameAndResource : filenamesAndResources) {
  				if(filenameAndResource.getbValue() != null) {
  					PropertiesHolder propHolder = getProperties(filenameAndResource.getaValue(), filenameAndResource.getbValue());
  					codes.addAll(propHolder.getProperties().stringPropertyNames());					
  				}
  			}
  		}
  		return codes;
  	}
docs: Retrieves all codes from one or multiple basenames
  @param locale the locale
  @param basenames the basenames of the bundle
  @return a list with all codes from valid registered bundles