this actually works

franklinmint-mule.xml

    <flow name="net_suite_test_flow">
        <http:inbound-endpoint ref="netsuite_test_endpoint" exchange-pattern="request-response"/>
        <logger message="#[groovy:return message.toString();]" level="INFO"/>
        <echo-component/>
        <netsuite:get-record recordType="INVENTORY_ITEM" id="#[header:INBOUND:internal_id]"/>
        <logger message="#[groovy:return message.toString();]" level="INFO"/>
        <expression-transformer>
            <return-argument evaluator="string" expression="Item: #[groovy:message.payload.storeDescription]"/>
        </expression-transformer>
        <netsuite:add-list recordType="CASH_SALE">
            <netsuite:records>
                <netsuite:record>
                    <tranDate>#[groovy: new Date()]</tranDate>
                    <entity>#[groovy: ['type' : 'CUSTOMER', 'externalId' : '301396', 'internalId' : '821'] ]</entity>
                    <itemList>#[groovy: ['item' : [['item' : ['type' : 'INVENTORY_ITEM', 'internalId' : '15'], 'quantity':'5']]]]</itemList>
                </netsuite:record>
            </netsuite:records>
        </netsuite:add-list>
    </flow>

Output:
https://gist.github.com/340736fdb0c4eb644fbe