mule-message-enricher.xml

<flow name="orderProcessingFlow">
   <inbound-endpoint ref="orderEndpoint"/>
   <enricher target="#[variable:state_short]">
       <outbound-endpoint ref="stateLookup">
           <expression-transformer evaluator="xpath" expression="/order/address/zip" />
       </outbound-endpoint>
   </enricher>
   <outbound-endpoint ref="orderStep2"/>
</flow>