Parameter tasks is deprecated, use target instead
<plugin>
<groupId></groupId>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.8</version>
<executions>
<execution>
<phase>clean</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<tasks>
<delete dir="${javadoc-output-dir}"/>
</tasks>
</configuration>
</execution>
</executions>
</plugin>