<plugin>
                <artifactId>maven-javadoc-plugin</artifactId>
                <version>2.8.1</version>
                <executions>
                    <execution>
                        <id>attach-javadocs</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>