code: public static Collection<String> listPackageResources(String packageName, String fileNamesPattern)
    {
      String packagePath = Files.dot2urlpath(packageName);
  
      Set<URL> packageURLs = new HashSet<>();
      for(ClassLoader classLoader : new ClassLoader[]
      {
          Thread.currentThread().getContextClassLoader(), Classes.class.getClassLoader(), ClassLoader.getSystemClassLoader()
      }) {
        try {
          packageURLs.addAll(Collections.list(classLoader.getResources(packagePath)));
        }
        catch(IOException e) {
          log.error(e);
        }
      }
      if(packageURLs.isEmpty()) {
        throw new NoSuchBeingException("Package |%s| not found.", packageName);
      }
  
      Set<String> resources = new HashSet<>();
      for(URL packageURL : packageURLs) {
        resources.addAll(listPackageResources(packageURL, packagePath, fileNamesPattern));
      }
      return resources;
    }
docs: List package resources from local classes or from archives. List resource file names that respect a given pattern
  from local stored package or from Java archive file. This utility method tries to locate the package with given
  name using {@link ClassLoader#getResources(String)}. If returned URL starts with <code>jar:file</code>, that is,
  has JAR protocol the package is contained into a Java archive file and is processed entry by entry. Otherwise
  protocol should be <code>file</code> and package is located into local classes and is processed as file. If
  protocol is neither <code>file</code> nor <code>jar:file</code> throws unsupported operation.
  
  @param packageName qualified package name, possible empty for package root,
  @param fileNamesPattern file names pattern as accepted by {@link FilteredStrings#FilteredStrings(String)}.
  @return collection of resources from package matching requested pattern, possible empty.
  @throws NoSuchBeingException if package is not found by current application class loader.
  @throws UnsupportedOperationException if found package URL protocol is not <code>file</code> or
  <code>jar:file</code>.