How to control if the current node is the primary polling instance

case6121-test-config.xml

    <flow name="main">
        <jms:inbound-endpoint queue="in" />

       	<!-- check if this application is running in the primary pooling instance -->
        <choice>
            <when evaluator="groovy" expression="muleContext.isPrimaryPollingInstance() == true">
                <!-- process the message -->
                <append-string-transformer message=" Received" />
                <logger level="INFO" message="#### IS PRIMARY POLLING INSTANCE, PROCESSING THE MESSAGE" />
                <vm:outbound-endpoint path="out"/>
            </when>
            <otherwise>
                <!-- put the message back in the queue (you'd need to copy the INBOUND PROPERTIES in the OUTBOUND SCOPE so you don't loose them)-->
                <jms:outbound-endpoint queue="in" />
            </otherwise>
        </choice>
        
    </flow>