尝试连接到REST API时收到有效负载错误

我希望调用内部REST API，并将有效负载传递回Mule 3.7.3。该请求仅是URL，没有任何正文，但是我收到了诸如nullPayload之类的有效载荷错误。

我怎样才能使它正常工作？

我正在使用此公共API https://apisandbox.openbankproject.com/obp/v2.0.0/banks对其进行测试

我模拟的代码在这里：

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:dw="http://www.mulesoft.org/schema/mule/ee/dw" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:tracking="http://www.mulesoft.org/schema/mule/ee/tracking" 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-3.7.3"
    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/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/ee/tracking http://www.mulesoft.org/schema/mule/ee/tracking/current/mule-tracking-ee.xsd
http://www.mulesoft.org/schema/mule/ee/dw http://www.mulesoft.org/schema/mule/ee/dw/current/dw.xsd">
    <http:listener-config name="HTTP_Listener_Configuration" host="0.0.0.0" port="8081" doc:name="HTTP Listener Configuration"/>
    <http:request-config name="HTTP_Request" host="https://apisandbox.openbankproject.com" port="443" basePath="/obp/v2.0.0" doc:name="HTTP Request Configuration"/>
    <flow name="account-balance-flow">
        <http:listener config-ref="HTTP_Listener_Configuration" path="/" allowedMethods="GET" doc:name="HTTP"/>
        <set-payload value="#['{}']" doc:name="Set Payload"/>
        <http:request config-ref="HTTP_Request" path="/banks" method="GET" doc:name="HTTP"/>
        <logger message="#[message.payload]" level="INFO" doc:name="Logger"/>
    </flow>
</mule>