public String getScheduleExpression() {
        return this.scheduleExpression;
    }
<p>
The expression that defines when the schedule runs. The following formats are supported.
</p>
<ul>
<li>
<p>
<code>at</code> expression - <code>at(yyyy-mm-ddThh:mm:ss)</code>
</p>
</li>
<li>
<p>
<code>rate</code> expression - <code>rate(value unit)</code>
</p>
</li>
<li>
<p>
<code>cron</code> expression - <code>cron(fields)</code>
</p>
</li>
</ul>
<p>
You can use <code>at</code> expressions to create one-time schedules that invoke a target once, at the time and
in the time zone, that you specify. You can use <code>rate</code> and <code>cron</code> expressions to create
recurring schedules. Rate-based schedules are useful when you want to invoke a target at regular intervals, such
as every 15 minutes or every five days. Cron-based schedules are useful when you want to invoke a target
periodically at a specific time, such as at 8:00 am (UTC+0) every 1st day of the month.
</p>
<p>
A <code>cron</code> expression consists of six fields separated by white spaces:
<code>(minutes hours day_of_month month day_of_week year)</code>.
</p>
<p>
A <code>rate</code> expression consists of a <i>value</i> as a positive integer, and a <i>unit</i> with the
following options: <code>minute</code> | <code>minutes</code> | <code>hour</code> | <code>hours</code> |
<code>day</code> | <code>days</code>
</p>
<p>
For more information and examples, see <a
href="https://docs.aws.amazon.com/scheduler/latest/UserGuide/schedule-types.html">Schedule types on EventBridge
Scheduler</a> in the <i>EventBridge Scheduler User Guide</i>.
</p>

@return The expression that defines when the schedule runs. The following formats are supported. </p>
        <ul>
        <li>
        <p>
        <code>at</code> expression - <code>at(yyyy-mm-ddThh:mm:ss)</code>
        </p>
        </li>
        <li>
        <p>
        <code>rate</code> expression - <code>rate(value unit)</code>
        </p>
        </li>
        <li>
        <p>
        <code>cron</code> expression - <code>cron(fields)</code>
        </p>
        </li>
        </ul>
        <p>
        You can use <code>at</code> expressions to create one-time schedules that invoke a target once, at the
        time and in the time zone, that you specify. You can use <code>rate</code> and <code>cron</code>
        expressions to create recurring schedules. Rate-based schedules are useful when you want to invoke a
        target at regular intervals, such as every 15 minutes or every five days. Cron-based schedules are useful
        when you want to invoke a target periodically at a specific time, such as at 8:00 am (UTC+0) every 1st
        day of the month.
        </p>
        <p>
        A <code>cron</code> expression consists of six fields separated by white spaces:
        <code>(minutes hours day_of_month month day_of_week year)</code>.
        </p>
        <p>
        A <code>rate</code> expression consists of a <i>value</i> as a positive integer, and a <i>unit</i> with
        the following options: <code>minute</code> | <code>minutes</code> | <code>hour</code> |
        <code>hours</code> | <code>day</code> | <code>days</code>
        </p>
        <p>
        For more information and examples, see <a
        href="https://docs.aws.amazon.com/scheduler/latest/UserGuide/schedule-types.html">Schedule types on
        EventBridge Scheduler</a> in the <i>EventBridge Scheduler User Guide</i>.
aws-java-sdk-scheduler/src/main/java/com/amazonaws/services/scheduler/model/UpdateScheduleRequest.java