docs: public static List<Path> getSubPathList(Path startDirectoryPath,
  			int maxDepth, Predicate<Path> filter) {
  		List<Path> subPathList =
  				Collections.synchronizedList(new ArrayList<>());
  		if (isDirectory(startDirectoryPath))
  			buildSubPath(startDirectoryPath, maxDepth, filter, subPathList);
  		return subPathList;
  	}