Error assembling WAR: webxml attribute is required (or pre-existing WEB-INF/web.xml if executing in update mode)

<plugins>  
    <plugin>  
        <groupId>org.apache.maven.plugins</groupId>  
        <artifactId>maven-war-plugin</artifactId>  
        <version>2.1.1</version>  
        <configuration>  
            <webResources>  
                <resource>                      
                <!-- this is relative to the pom.xml directory -->  
                <directory>WebContent</directory>  
                </resource>  
            </webResources>  
        </configuration>  
    </plugin>  
</plugins>