Transform.xml

<api xmlns="http://ws.apache.org/ns/synapse" name="Transform" context="/Transform">
   <resource methods="POST">
      <inSequence>
         <property name="messageType" value="application/json" scope="axis2"></property>
         <log level="custom">
            <property name="Status" expression="json-eval($.StockQuotes.Stock)"></property>
         </log>
         <filter source="json-eval($.StockQuotes.Stock.Symbol)" regex="null">
            <then>
               <payloadFactory media-type="json">
                  <format>{ "StockQuotes": { "Stock":  $1 } }</format>
                  <args>
                     <arg evaluator="json" expression="$.StockQuotes.Stock"></arg>
                  </args>
               </payloadFactory>
            </then>
            <else>
               <payloadFactory media-type="json">
                  <format>{ "StockQuotes": { "Stock": [ $1 ] } }</format>
                  <args>
                     <arg evaluator="json" expression="$.StockQuotes.Stock"></arg>
                  </args>
               </payloadFactory>
            </else>
         </filter>
         <respond></respond>
      </inSequence>
   </resource>
</api>