Need help setting variable in Camel - xpath

Question

I am trying to set a variable inside of my camel code so I can call this variable when I log my route execution. This variable needs to be set from an xpath statement.
Below is the code that is not working and I suspect that I need to set a variable that is equal to my xpath statement that is found in the log message but I don't know how to do that.
<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:camel="http://camel.apache.org/schema/blueprint"
xsi:schemaLocation="
http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
http://camel.apache.org/schema/blueprint http://camel.apache.org/schema/blueprint/camel-blueprint.xsd">
<bean id="activemq"
class="org.apache.activemq.camel.component.ActiveMQComponent">
<property name="brokerURL" value="tcp://localhost:61616"/>
<property name="userName" value="user"/>
<property name="password" value="password"/>
</bean>
<camelContext id="blueprintContext" trace="false" xmlns="http://camel.apache.org/schema/blueprint">
<route id="Test_Message_Content_Route">
<from uri="activemq:queue:FirstQueue?username=user&password=password&concurrentConsumers=1&maxConcurrentConsumers=5"/>
<choice>
<when>
<xpath>//destination[text()='TEST']</xpath>
<log message="Test route invoked"/>
<split>
<xpath resultType="java.lang.String">//message_payload/text()</xpath>
<log message="Routed $xpath{//id/text()} to TEST QUEUE"/>
<to uri="activemq:queue:TestQueue?username=user&password=password"/>
</split>
</when>
<when>
<xpath>//destination[text()='DEV']</xpath>
<log message="Dev route invoked"/>
<split>
<xpath resultType="java.lang.String">//message_payload/text()</xpath>
<log message="Routed $xpath{//id/text()} to DEV QUEUE"/>
<to uri="activemq:queue:DevQueue?username=user&password=password"/>
</split>
</when>
<otherwise>
<log message="Sending message to DL Queue"/>
<to uri="activemq:queue:DLQueue?username=user&password=password"/>
</otherwise>
</choice>
</route>
</camelContext>
</blueprint>

Answer 1

I now have this working by using setHeader in my camel context like the following:
<setHeader headerName="id"><xpath>//id/text()</xpath></setHeader>
<log message="Routed ${header.id} to Test queue"/>