code: @VisibleForTesting
      static Function<CronField, CronField> returnOnZeroExpression(final CronFieldName name) {
          return field -> {
              final FieldConstraints constraints = FieldConstraintsBuilder.instance().forField(name).createConstraintsInstance();
              return new CronField(name, new On(new IntegerFieldValue(0)), constraints);
          };
      }
docs: Creates a Function that returns a On instance with zero value.
  
  @param name - Cron field name
  @return new CronField -> CronField instance, never null