Getting 0% coverage report using jacoco-gwt-maven-plugin? - maven

Question

I am trying to get coverage report of GWTTestCases using jacoco-gwt-maven-plugin.
I followed the below link:
https://github.com/errai/jacoco-gwt-maven-plugin
pom.xml
<build>
<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<version>2.7.0</version>
<executions>
<execution>
<configuration>
<extraJvmArgs>-Xmx512m</extraJvmArgs>
</configuration>
<goals>
<goal>compile</goal>
<goal>generateAsync</goal>
<goal>test</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.jboss.errai</groupId>
<artifactId>jacoco-gwt-maven-plugin</artifactId>
<version>0.5.4.201202141554</version>
<configuration>
<snapshotDirectory>${project.build.directory}/test-classes</snapshotDirectory>
<propertyName>jacocoArgs</propertyName>
</configuration>
<executions>
<execution>
<id>jacoco-initialize</id>
<goals>
<goal>prepare-agent</goal>
</goals>
</execution>
<execution>
<id>jacoco-site</id>
<phase>package</phase>
<goals>
<goal>report</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.6</version>
<configuration>
<argLine>${jacocoArgs}</argLine>
</configuration>
</plugin>
</plugins>
</build>
When I run the Project using commands as,
mvn clean
mvn install
Inside target folder I can see,
site Directory --> jacoco Directory --> index.html file gets created.
When I open index.html, code coverage is 0%.
What I am doing wrong, Please help.
I got some help from link below, but still struggling to get complete report
How do I setup coverage with GWT, maven, jacoco?
In target\test-classes folder I can see only GwtTestCovergeSample.class file from test package, does client and server folder class files should also be present here?