在Spring Boot AWS Context中使用简单凭证时出错-Bean已绑定

Question

给出我的applicationContext.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
		     xmlns:context="http://www.springframework.org/schema/context"
		     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
		     xmlns:aws-context="http://www.springframework.org/schema/cloud/aws/context"
		     xsi:schemaLocation="http://www.springframework.org/schema/beans 
		     http://www.springframework.org/schema/beans/spring-beans-4.1.xsd 
		     http://www.springframework.org/schema/context 
		     http://www.springframework.org/schema/context/spring-context-5.1.xsd
			 http://www.springframework.org/schema/cloud/aws/context 
			 http://www.springframework.org/schema/cloud/aws/context/spring-cloud-aws-context.xsd">

    <aws-context:context-credentials>
        <aws-context:instance-profile-credentials/>
        <aws-context:simple-credentials access-key="${aws.accessKeyId}" secret-key="${aws.secretKey}"/>
    </aws-context:context-credentials>
    
</beans>

此错误：

以null定义的bean'credentialsProvider'无法注册。具有该名称的bean已被定义为null，并且禁用了覆盖。

xml有什么问题？