public String getExpressionSummary() {
        StringBuilder buf = new StringBuilder();

        buf.append("seconds: ");
        buf.append(getExpressionSetSummary(seconds));
        buf.append("\n");
        buf.append("minutes: ");
        buf.append(getExpressionSetSummary(minutes));
        buf.append("\n");
        buf.append("hours: ");
        buf.append(getExpressionSetSummary(hours));
        buf.append("\n");
        buf.append("daysOfMonth: ");
        buf.append(getExpressionSetSummary(daysOfMonth));
        buf.append("\n");
        buf.append("months: ");
        buf.append(getExpressionSetSummary(months));
        buf.append("\n");
        buf.append("daysOfWeek: ");
        buf.append(getExpressionSetSummary(daysOfWeek));
        buf.append("\n");
        buf.append("lastdayOfWeek: ");
        buf.append(lastdayOfWeek);
        buf.append("\n");
        buf.append("nearestWeekday: ");
        buf.append(nearestWeekday);
        buf.append("\n");
        buf.append("NthDayOfWeek: ");
        buf.append(nthdayOfWeek);
        buf.append("\n");
        buf.append("lastdayOfMonth: ");
        buf.append(lastdayOfMonth);
        buf.append("\n");
        buf.append("years: ");
        buf.append(getExpressionSetSummary(years));
        buf.append("\n");

        return buf.toString();
    }
Indicates whether the specified cron expression can be parsed into a
valid cron expression

@param cronExpression the expression to evaluate
@return a boolean indicating whether the given expression is a valid cron
        expression
server/core/src/main/java/com/ke/schedule/server/core/common/CronExpression.java