code: public static String localTimeToString(LocalTime time, String emptyTimeString) {
          return (time == null) ? emptyTimeString : time.toString();
      }
docs: localTimeToString, This will return the supplied time as a string. If the time is null, this
  will return the value of emptyTimeString.
  
  Time values will be output in one of the following ISO-8601 formats: "HH:mm", "HH:mm:ss",
  "HH:mm:ss.SSS", "HH:mm:ss.SSSSSS", "HH:mm:ss.SSSSSSSSS".
  
  The format used will be the shortest that outputs the full value of the time where the
  omitted parts are implied to be zero.
  </code>