How do I include ScalaDoc options in Maven

Question

I can generate class hierarchy diagram by manually use "scaladoc -diagrams ..."

I can also generate basic ScalaDoc with Maven by "mvn scala:doc"

But How can I put "-diagrams" in when I run ScalaDoc from Maven? In general, how do I put in any of the options that are listed in "scaladoc -help".

I have this in my pom.xml, but it doesn't work.

        <plugin>
            <groupId>org.scala-tools</groupId>
            <artifactId>maven-scala-plugin</artifactId>
            <version>2.14-SNAPSHOT</version>
            <configuration>
                <args>
                    <arg>-diagrams</arg>
                </args>
            </configuration>
         </plugin>

UPDATE

This doesn't work either:

        <plugin>
            <groupId>org.scala-tools</groupId>
            <artifactId>maven-scala-plugin</artifactId>

            <executions>
                <execution>
                    <id>generate-scaladoc</id>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>doc</goal>
                    </goals>
                    <configuration>
                        <diagrams>true</diagrams>
                        <args>
                            <arg>-diagrams</arg>
                        </args>
                    </configuration>
                </execution>
            </executions>
      </plugin>

Answer 1

I could generate java-docs for scala maven project using the scala-maven-plugin's attach-javadocs execution as shown below:

                 <plugin>
                    <groupId>net.alchim31.maven</groupId>
                    <artifactId>scala-maven-plugin</artifactId>
                    <version>3.2.0</version>
                    <executions>
                        <execution>
                            <!-- this is so we don't end with a compile error in maven-compiler-plugin -->
                            <phase>process-sources</phase>
                            <goals>
                                <goal>compile</goal>
                                <goal>testCompile</goal>
                            </goals>
                            <configuration>
                            </configuration>
                        </execution>
                        <execution>
                            <id>attach-javadocs</id>
                            <goals>
                                <goal>doc-jar</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>

Once the above specified plugin config is added, just run mvn clean install and it'll generate javadoc's jar along with sources jar