在mule esb中使用java 8流时出现错误的表达式错误

<expression-transformer>
    <return-argument evaluator="groovy" expression="#[payload.collect { it.toUpperCase() }]"/>
</expression-transformer>

<scripting:component>
    <scripting:script engine="Groovy">
        <![CDATA[
            import java.util.stream.Collectors;
            
            payload = payload.stream()
                             .map { it.toUpperCase() }
                             .collect(Collectors.toList());
        ]]>
    </scripting:script>
</scripting:component>

<expression-transformer>
    <return-argument evaluator="groovy" expression="#[payload.stream().filter { it instanceof String }.collect(Collectors.toList())]"/>
</expression-transformer>

<logger message="Payload before transformation: #[payload]" level="INFO"/>
<scripting:component>
    <scripting:script engine="Groovy">
        <![CDATA[
            payload = payload.stream()
                             .map { it.toUpperCase() }
                             .collect(Collectors.toList());
        ]]>
    </scripting:script>
</scripting:component>
<logger message="Payload after transformation: #[payload]" level="INFO"/>