Maven和java:如何从test目录中的protobuf文件生成代码？

<build>
  <plugins>
    <plugin>
      <groupId>org.xolstice.maven.plugins</groupId>
      <artifactId>protobuf-maven-plugin</artifactId>
      <version>0.6.1</version>
      <configuration>
        <protocExecutable>protoc</protocExecutable>
        <pluginId>java</pluginId>
        <pluginArtifact>com.google.protobuf:protobuf-java</pluginArtifact>
        <protoSourceRoot>${project.basedir}/src/test/proto</protoSourceRoot>
        <outputDirectory>${project.build.directory}/generated-sources/test/java</outputDirectory>
      </configuration>
      <executions>
        <execution>
          <goals>
            <goal>compile</goal>
            <goal>test-compile</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

mvn protobuf:compile
mvn protobuf:test-compile