Maven pom封装模块上的cobertura

我有一个多模块maven项目。我想为网站生成一个聚合的cobertura报告。im运行的模块

mvn site

是pom打包的，所以maven在生成站点时给我这个

[INFO] >>> cobertura-maven-plugin:2.5.1:cobertura (report:cobertura) @ parent >>>
[INFO] 
[INFO] --- cobertura-maven-plugin:2.5.1:instrument (report:cobertura) @ parent ---
[INFO] Skipping cobertura mojo for project with packaging type 'pom'
[INFO] 
[INFO] <<< cobertura-maven-plugin:2.5.1:cobertura (report:cobertura) @ parent <<<
[INFO] Not executing cobertura:report as the cobertura data file (/home/user/parent/target/cobertura/cobertura.ser) could not be found

[INFO]>>>cobertura maven插件：2.5.1:cobertura（报告：cobertura）@parent>>
[信息]
[信息]---cobertura maven插件：2.5.1:instrument（报告：cobertura）@parent---
[信息]跳过包装类型为“pom”的项目的cobertura mojo
[信息]
[信息]在配置部分使用：

 <forceMojoExecution>true</forceMojoExecution>

true
在报告生成中，我们应该启用输出格式html，如下所示

<reporting>
  <plugins>
....
    <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>cobertura-maven-plugin</artifactId>
        <version>2.6</version>
        <configuration>
            <formats>
                <format>html</format>
                <format>xml</format>
            </formats>
        </configuration>
    </plugin>

       </plugins>
    </reporting>


....
org.codehaus.mojo
cobertura maven插件
2.6
html
xml
ForceMooJo执行似乎不起作用。有解决办法吗？
<reporting>
  <plugins>
....
    <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>cobertura-maven-plugin</artifactId>
        <version>2.6</version>
        <configuration>
            <formats>
                <format>html</format>
                <format>xml</format>
            </formats>
        </configuration>
    </plugin>

       </plugins>
    </reporting>