Generate javadoc site :

> mvn clean javadoc:javadoc

We can specify classes which we want to be included in the javadoc, for that add in build>plugins section following:

      <plugin>
        <groupid>org.apache.maven.plugins</groupid>
        <artifactid>maven-javadoc-plugin</artifactid>
        <version>2.9</version>
        <configuration>
                <sourcefileincludes>
                        <include>DelegationUtils.java</include>
                </sourcefileincludes>
                <sourcepath>${basedir}/src/path_to_package1;${basedir}/src/path_to_package2;</sourcepath>
        </configuration>
      </plugin>

Note that previous configuration is handled by 2.9 version or prior of maven javadoc plugin
then regenarate java doc :

> mvn clean javadoc:javadoc