@VisibleForTesting
static Function<CronField, CronField> returnOnZeroExpression(final CronFieldName name){
return new Function<CronField, CronField>() {
@Override
public CronField apply(CronField field) {
return new CronField(name, new On(FieldConstraintsBuilder.instance().forField(name).createConstraintsInstance(),"0"));
}
};
}