}

    private List<SourceFolder> externalSourceFolders(String... paths) {
        javaTree = dirTree("src", [], [])
        resourcesTree = dirTree("resources", [], [])

        def allExtTrees = paths.collect { path -> dirTree(path, [], []) }

        _ * java.srcDirs >> allExtTrees.collect { it.dir } + javaTree.dir
        _ * java.srcDirTrees >> allExtTrees + javaTree