public void setArn(String arn) {
        this.arn = arn;
    }
<p>
The Amazon Resource Name (ARN) of an Amazon Simple Notification Service (Amazon SNS) topic where notifications
are sent when this OpsItem is edited or changed.
</p>

@param arn
       The Amazon Resource Name (ARN) of an Amazon Simple Notification Service (Amazon SNS) topic where
       notifications are sent when this OpsItem is edited or changed.
aws-java-sdk-ssm/src/main/java/com/amazonaws/services/simplesystemsmanagement/model/OpsItemNotification.java