Scala Maven projects with multiple source folders

I had a need on a recent scala based maven project to be able to support multiple source folders - to hold the scala and java source and tests separately."Build Helper" Maven plugin perfectly fit this need, the following is a sample pom.xml configured using this plugin:

There are two sources - src/main/java holding the java code, and src/main/scala holding the scala code

and two test sources - src/test/java, src/test/scala.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>org.bk</groupId>
<artifactId>trainroute</artifactId>
<version>1.0-SNAPSHOT</version>
<build>
    <sourceDirectory>src/main/scala</sourceDirectory>
    <testSourceDirectory>src/test/scala</testSourceDirectory>
    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.scala-tools</groupId>
            <artifactId>maven-scala-plugin</artifactId>
            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                        <goal>testCompile</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <scalaVersion>${scala.version}</scalaVersion>
            </configuration>
        </plugin>
  <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>1.3</version>
    <executions>
      <execution>
        <id>add-source</id>
        <phase>generate-sources</phase>
        <goals>
          <goal>add-source</goal>
        </goals>
        <configuration>
          <sources>
            <source>src/main/java</source>
          </sources>
        </configuration>
      </execution>
      <execution>
        <id>add-test-source</id>
        <phase>generate-sources</phase>
        <goals>
          <goal>add-test-source</goal>
        </goals>
        <configuration>
          <sources>
            <source>src/test/java</source>
          </sources>
        </configuration>
      </execution>
    </executions>
  </plugin>        
    </plugins>
</build>
<dependencies>
    <dependency>
        <groupId>org.scala-lang</groupId>
        <artifactId>scala-library</artifactId>
        <version>${scala.version}</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
        <scope>test</scope>
    </dependency>
</dependencies>
<properties>
    <scala.version>2.7.6</scala.version>
    <junit.version>4.6</junit.version>
</properties>

<repositories>
    <repository>
        <id>scala-tools.org</id>
        <name>Scala-tools Maven2 Repository</name>
        <url>http://scala-tools.org/repo-releases</url>
    </repository>
</repositories>
<pluginRepositories>
    <pluginRepository>
        <id>scala-tools.org</id>
        <name>Scala-tools Maven2 Repository</name>
        <url>http://scala-tools.org/repo-releases</url>
    </pluginRepository>
</pluginRepositories>
</project>