public void setPreferredMaintenanceWindow(String preferredMaintenanceWindow) {
        this.preferredMaintenanceWindow = preferredMaintenanceWindow;
    }
<p>
The weekly time range during which system maintenance can occur, in Universal Coordinated Time (UTC).
</p>
<p>
Format: <code>ddd:hh24:mi-ddd:hh24:mi</code>
</p>
<p>
The default is a 30-minute window selected at random from an 8-hour block of time for each Amazon Region,
occurring on a random day of the week. To see the time blocks available, see <a href=
"https://docs.aws.amazon.com/neptune/latest/userguide/manage-console-maintaining.html#manage-console-maintaining-window"
>Neptune Maintenance Window</a> in the <i>Amazon Neptune User Guide.</i>
</p>
<p>
Valid Days: Mon, Tue, Wed, Thu, Fri, Sat, Sun.
</p>
<p>
Constraints: Minimum 30-minute window.
</p>

@param preferredMaintenanceWindow
       The weekly time range during which system maintenance can occur, in Universal Coordinated Time (UTC).</p>
       <p>
       Format: <code>ddd:hh24:mi-ddd:hh24:mi</code>
       </p>
       <p>
       The default is a 30-minute window selected at random from an 8-hour block of time for each Amazon Region,
       occurring on a random day of the week. To see the time blocks available, see <a href=
       "https://docs.aws.amazon.com/neptune/latest/userguide/manage-console-maintaining.html#manage-console-maintaining-window"
       >Neptune Maintenance Window</a> in the <i>Amazon Neptune User Guide.</i>
       </p>
       <p>
       Valid Days: Mon, Tue, Wed, Thu, Fri, Sat, Sun.
       </p>
       <p>
       Constraints: Minimum 30-minute window.
aws-java-sdk-neptune/src/main/java/com/amazonaws/services/neptune/model/CreateDBClusterRequest.java