What kind of Java plugin? A basic Java program? In this case, you should include the Maven dependency:
<dependency>
<groupId>org.walkmod</groupId>
<artifactId>walkmod-cmd</artifactId>
<version>2.2.0</version>
</dependency>
An then, use the WalkModFacade class methods. I would like to know which is the difference of using your Java program than walkmod directly. Could you explain this a little bit? Remember that Walkmod is LGPL v3 and therefore, your code as well.