docs: @Nullable
    public static String resolveFilename(final String baseDir, @Nullable final String filename) {
  
      if (filename != null) {
        // Normalization can return null if path is null, is invalid,
        // or is a path with back-ticks outside known directory structure
        String normalizedPath = FilenameUtils.normalize(filename);
        if ((normalizedPath != null) && (new File(normalizedPath).isAbsolute())) {
          return normalizedPath;
        }
  
        // Prefix with absolute module base directory, attempt normalization again -- can still get null here
        normalizedPath = FilenameUtils.normalize(baseDir + File.separator + filename);
        if (normalizedPath != null) {
          return normalizedPath;
        }
      }
      return null;
    }