使用maven-compiler-plugin 時,報如下提示，字面意思就是沒有指定版本資訊

[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.xxx.xxx:xxxx:jar:0.0.1-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ line 72, column 12
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING] 
 

<plugins>  
    <plugin>  
        <artifactId>maven-compiler-plugin</artifactId>  
        <configuration>  
            <source>1.6</source>  
            <target>1.6</target>  
            <encoding>UTF-8</encoding>  
        </configuration>  
    </plugin>  
</plugins
 

    <plugins>  
            <plugin>  
                <artifactId>maven-compiler-plugin</artifactId>  
                <version>2.3.2</version>  
                <configuration>  
                    <source>1.6</source>  
                    <target>1.6</target>  
                    <encoding>UTF-8</encoding>  
                </configuration>  
            </plugin>  
        </plugins>  
 

來自：http://qiang106.iteye.com/blog/1388645