code: @Nonnull
    @ReturnsMutableCopy
    public static ICommonsList <Path> getDirectoryContent (@Nonnull final Path aDirectory,
                                                           @Nullable final Predicate <? super Path> aPathFilter)
    {
      ValueEnforcer.notNull (aDirectory, "Directory");
  
      return _getDirectoryContent (aDirectory, aPathFilter);
    }
docs: This is a replacement for <code>Path.listFiles(FilenameFilter)</code> doing
  some additional checks on permissions. The order of the returned files is
  undefined. "." and ".." are not contained.
  
  @param aDirectory
  The directory to be listed. May not be <code>null</code>.
  @param aPathFilter
  The path filter to be used. May not be <code>null</code>.
  @return Never <code>null</code>.