Cannot change version of project facet Dynamic Web Module to 2.4

navigator视图下打开工程，修改.setting目录下的org.eclipse.wst.common.project.facet.core.xml文件

内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<faceted-project>
  <fixed facet="wst.jsdt.web"/>
  <installed facet="java" version="1.7"/>
  <installed facet="jst.web" version="2.4"/>
  <installed facet="jst.jaxrs" version="1.1"/>
  <installed facet="wst.jsdt.web" version="1.0"/>
</faceted-project>

然后执行项目右键Maven的Update Project...即可