Found it in an alternate way..works great.!
Steps include
1. Removed build-helper-maven-plugin from pom .
2. Created another maven project and added the common classes in it. Added maven-source-plugin in this pom to generate sources.
3. To the same pom, added maven-dependency-plugin to copy this generated sources to the desired location (My project's src/main/java).
4. Run a maven build for common classes project.
Now the common code in my project. Thanks.