code: private String dateToExplicitTimestampUTC( Date date )
      {
          DateFormat df = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" );
          df.setTimeZone( TimeZone.getTimeZone( "UTC" ) );
          return "TS: " + df.format( date ) + "Z";
      }
docs: Converts a given date to an explicit timestamp string in UTC time zone.
  
  @param date a timestamp to convert.
  @return a string representing a timestamp.