liquibase-core/src/main/java/liquibase/change/ColumnConfig.java
public ColumnConfig setValueDate(String valueDate) throws DateParseException {
        if ((valueDate == null) || "null".equalsIgnoreCase(valueDate)) {
            this.valueDate = null;
        } else if (NowAndTodayUtil.isNowOrTodayFormat(valueDate)) {
            this.valueDate = NowAndTodayUtil.doNowOrToday(valueDate, this.getType());
        } else {
            try {
                this.valueDate = new ISODateFormat().parse(valueDate);
            } catch (ParseException e) {
                //probably a function
                this.valueComputed = new DatabaseFunction(valueDate);
            }
        }

        return this;
    }
public ColumnConfig setValueDate(String valueDate) throws DateParseException {
        if ((valueDate == null) || "null".equalsIgnoreCase(valueDate)) {
            this.valueDate = null;
        } else if (NowAndTodayUtil.isNowOrTodayFormat(valueDate)) {
            this.valueDate = NowAndTodayUtil.doNowOrToday(valueDate, this.getType());
        } else {
            try {
                this.valueDate = new ISODateFormat().parse(valueDate);
            } catch (ParseException e) {
                //probably a function
                this.valueComputed = new DatabaseFunction(valueDate);
            }
        }

        return this;
    }
Set the date this column should be set to. Supports any of the date or datetime formats handled by {@link ISODateFormat}.
If the passed value cannot be parsed as a date, it is assumed to be a function that returns a date.
If the string "null" is passed, it will set a null value.
@param valueDate the Date Value to use (may be null or "null", or start with "now" or "today".
@throws DateParseException if the columnType isn't supported for "now" or "today" values.