public void setArn(String arn) {
        this.arn = arn;
    }
<p>
The unique identifier for the event. The event ARN has the
<code>arn:aws:health:<i>event-region</i>::event/<i>SERVICE</i>/<i>EVENT_TYPE_CODE</i>/<i>EVENT_TYPE_PLUS_ID</i> </code>
format.
</p>
<p>
For example, an event ARN might look like the following:
</p>
<p>
<code>arn:aws:health:us-east-1::event/EC2/EC2_INSTANCE_RETIREMENT_SCHEDULED/EC2_INSTANCE_RETIREMENT_SCHEDULED_ABC123-DEF456</code>
</p>

@param arn
       The unique identifier for the event. The event ARN has the
       <code>arn:aws:health:<i>event-region</i>::event/<i>SERVICE</i>/<i>EVENT_TYPE_CODE</i>/<i>EVENT_TYPE_PLUS_ID</i> </code>
       format.</p>
       <p>
       For example, an event ARN might look like the following:
       </p>
       <p>
       <code>arn:aws:health:us-east-1::event/EC2/EC2_INSTANCE_RETIREMENT_SCHEDULED/EC2_INSTANCE_RETIREMENT_SCHEDULED_ABC123-DEF456</code>
aws-java-sdk-health/src/main/java/com/amazonaws/services/health/model/Event.java