public void setStateTransitionedTimestamp(java.util.Date stateTransitionedTimestamp) {
        this.stateTransitionedTimestamp = stateTransitionedTimestamp;
    }
<p>
The timestamp of the last change to the alarm's <code>StateValue</code>.
</p>

@param stateTransitionedTimestamp
       The timestamp of the last change to the alarm's <code>StateValue</code>.
aws-java-sdk-cloudwatch/src/main/java/com/amazonaws/services/cloudwatch/model/CompositeAlarm.java