Eclipse2021中web.xml报错

报错内容：
cvc-id.3: A field of identity constraint '...' matched element 'web-app', but this element does not have a simple type
具体可能如下
cvc-id.3: A field of identity constraint 'web-common-filter-name-uniqueness' matched element 'web-app', but this element does not have a simple type
或者
cvc-id.3: A field of identity constraint 'web-app-servlet-name-uniqueness' matched element 'web-app', but this element does not have a simple type

推荐写法：
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">

报错原因：内容冲突，删除其一

 访问该网址http://java.sun.com/xml/ns/javaee，检索web-app_3_0.xsd，下载文件可查看推荐写法