Skip copying resources

How do I skip copying resources? I try <skip> in <configuration> but it does not work.

<plugin>
<artifactId>maven-resources-plugin</artifactId>
<executions>
<execution>
<id>copy-xxx</id>
<phase>compile</phase>
<goals>
<goal>copy-resources</goal>
</goals>
<configuration>
<skip>true</skip>
<outputDirectory>${webapp.dir}/example/resources</outputDirectory>
<resources>
<resource>
<directory>${webapp.dir}/resources</directory>
<includes>
<include>**</include>
</includes>
</resource>
</resources>
</configuration>
</execution>
</executions>

Joncheng Kuo