如何在Mulesoft中比较Xml中json对象值

<mule xmlns:json="http://www.mulesoft.org/schema/mule/json" xmlns:xpath="http://www.mulesoft.org/schema/mule/xpath" xmlns:dw="http://www.mulesoft.org/schema/mule/ee/dw" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
    xmlns:spring="http://www.springframework.org/schema/beans" version="EE-4.3.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
        http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
        http://www.mulesoft.org/schema/mule/xpath http://www.mulesoft.org/schema/mule/xpath/current/mule-xpath.xsd
        http://www.mulesoft.org/schema/mule/json http://www.mulesoft.org/schema/mule/json/current/mule-json.xsd
        http://www.mulesoft.org/schema/mule/ee/dw http://www.mulesoft.org/schema/mule/ee/dw/current/dw.xsd">
        
    <flow name="compare-json-values">
        <http:listener config-ref="HTTP_Listener_Configuration" path="/compare" allowedMethods="GET" doc:name="HTTP"/>
        <set-payload value="#[getResource('input.xml').asStream()]" doc:name="Set Payload"/>
        
        <!-- 使用XPath表达式提取JSON对象 -->
        <xpath:transformer returnClass="java.lang.String" expression="//json:jsonObject" doc:name="Extract JSON Object"/>
        
        <!-- 使用MEL比较JSON对象的值 -->
        <choice doc:name="Choice">
            <when expression="#[json:jsonPath(payload, '$.key') == 'value']">
                <logger level="INFO" message="JSON object value is equal to 'value'" doc:name="Logger"/>
            </when>
            <otherwise>
                <logger level="INFO" message="JSON object value is not equal to 'value'" doc:name="Logger"/>
            </otherwise>
        </choice>
    </flow>
</mule>