Multiple annotations found at this line:
- Attribute "version" must be declared for element type "web-app".
- Attribute "xsi:schemaLocation" must be declared for element type
"web-app".
- Attribute "xmlns:xsi" must be declared for element type "web-app".
- Attribute "xmlns" must be declared for element type "web-app".
这种错误就是要求web-app的标签必须在第一行,即使这里前面是无关的版本号注释也不行,删除前面的版本号,让web-app第一行即可解决。