docs: public static File checkSlip(File parentFile, File file) throws IllegalArgumentException {
  		if (null != parentFile && null != file) {
  			String parentCanonicalPath;
  			String canonicalPath;
  			try {
  				parentCanonicalPath = parentFile.getCanonicalPath();
  				canonicalPath = file.getCanonicalPath();
  			} catch (IOException e) {
  				throw new IORuntimeException(e);
  			}
  			if (false == canonicalPath.startsWith(parentCanonicalPath)) {
  				throw new IllegalArgumentException("New file is outside of the parent dir: " + file.getName());
  			}
  		}
  		return file;
  	}