code: static Duration parseDuration(final String string) {
  		return string != null
  			? Duration.ofSeconds(Long.parseLong(string))
  			: null;
  	}
docs: Convert the given {@code object} into a duration value. If the
  {@code object} is {@code null}, {@code null} is returned.
  
  @param string the object to convert
  @return the converted object