是否有必要在pom中指定maven插件的版本？

Question

I am using NetBeans for development and it has built-in menu feature that allows us to add maven-checkstyle-plugin in the pom for code formatting . However, when you click on that menu it add the following piece of code in the pom automatically but without the <version> information. Now my IDE keeps on complaining with a small hint message in the margin saying that the 'version' tag is missing. My question is: Does all plugins added has to have a <version> tag in the pom?

pom.xml

 <reporting>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
                <configuration>
                    <configLocation>config/sun_checks.xml</configLocation>
                </configuration>
            </plugin>
        </plugins>
    </reporting>

Answer 1

It is not necessary, but highly recommended to use the version tag.

When a plugin was invoked without an explicit version given in the POM or on the command line, Maven 2.x used to pick the latest version available where the latest version could either be a release or a snapshot. For the sake of stability, Maven 3.x prefers the latest release version over the latest snapshot version.

Given the threat of non-reproducible builds imposed by automatic plugin version resolution, this feature is scheduled for removal as far as plugin declarations in the POM are concerned. Users of Maven 3.x will find it output a warning when missing plugin versions are detected to encourage the addition of plugin versions to the POM or one of its parent POMs. The Enforcer rule requirePluginVersions can be used additionally check for missing plugin versions in the POM.

https://cwiki.apache.org/confluence/display/MAVEN/Maven+3.x+Compatibility+Notes