code: public static String format(Instant time, DateTimeFormatter format) {
  
  		if (format == null) {
  			return formatDateTime(time);
  		}
  
  		Assert.notNull(time, "Missing time!");
  		return format.format(time);
  	}
docs: Custom date time format
  
  @param time   to be formatted
  @param format simple date time format, or null for default yyyy-MM-dd HH:mm:ss Z format
  @return formated date time