code: public String describeHHmmss(final Map<CronFieldName, CronField> fields) {
          return DescriptionStrategyFactory.hhMMssInstance(
                  resourceBundle,
                  fields.containsKey(CronFieldName.HOUR) ? fields.get(CronFieldName.HOUR).getExpression() : null,
                  fields.containsKey(CronFieldName.MINUTE) ? fields.get(CronFieldName.MINUTE).getExpression() : null,
                  fields.containsKey(CronFieldName.SECOND) ? fields.get(CronFieldName.SECOND).getExpression() : null
          ).describe();
      }
docs: Provide description for hours, minutes and seconds.
  
  @param fields - fields to describe;
  @return description - String