src/it/projects/multimodule/two-levels-includeBaseDir-withSrc/src/assemble/src.xml

<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 http://maven.apache.org/xsd/assembly-1.1.0.xsd">
  <id>src</id>
  <formats>
    <format>dir</format>
  </formats>
  <includeBaseDirectory>true</includeBaseDirectory>
  <moduleSets>
    <moduleSet>
      <includeSubModules>true</includeSubModules>

      <sources>
        <excludeSubModuleDirectories>true</excludeSubModuleDirectories>
        <includeModuleDirectory>true</includeModuleDirectory>
        <outputDirectoryMapping>modules/${module.artifactId}</outputDirectoryMapping>

        <fileSets>
          <fileSet>
            <excludes>
              <exclude>**/target/**</exclude>
              <exclude>**/.svn/**</exclude>
            </excludes>
          </fileSet>
        </fileSets>
      </sources>
    </moduleSet>
  </moduleSets>
</assembly>