'checkstyle:checkstyle-optional:4.1'
<dependency>
<groupId>checkstyle</groupId>
<artifactId>checkstyle-optional</artifactId>
<version>4.1</version>
</dependency>
<dependency org="checkstyle" name="checkstyle-optional" rev="4.1"/>
"checkstyle", "checkstyle-optional", "4.1"