@TaskAction
                void run() {
                    def input = inputDirectory.file("output.txt").get().asFile
                    if (input.file) {
                        outputFile.asFile.get().text = input.text
                    } else {
                        outputFile.asFile.get().text = "<empty>"
                    }
                }
            }

            task sourceTask(type: Producer) {

        return gson.toJson(subprojects) + '\n'
    }

    private
    fun generateSubprojectsDirectories(): List<File> {
        val subprojectRoots = platformsFolder.asFile.listFiles(File::isDirectory).plus(subprojectsFolder.asFile).plus(testingFolder.asFile)
        return subprojectRoots.map { it.listFiles(File::isDirectory).asList() }.flatten()
    }

    private
    fun generateSubprojects(): List<GradleSubproject> {

        srcDir = projectDirectory.file('src').asFile
        println "Contents of $srcDir.name"
        collection.collect { projectDirectory.asFile.relativePath(it) }.sort().each { println it }

        srcDir = projectDirectory.file('src2').asFile
        println "Contents of $srcDir.name"
        collection.collect { projectDirectory.asFile.relativePath(it) }.sort().each { println it }
    }
}
// end::closure[]

        })

        srcDir = projectDirectory.file("src").asFile
        println("Contents of ${srcDir.name}")
        collection.map { it.relativeTo(projectDirectory.asFile) }.sorted().forEach { println(it) }

        srcDir = projectDirectory.file("src2").asFile
        println("Contents of ${srcDir.name}")
        collection.map { it.relativeTo(projectDirectory.asFile) }.sorted().forEach { println(it) }
    }
}
// end::closure[]

                def produce() {
                    dirName.get().asFile.text = 'dir'
                }
            }

            abstract class Consumer extends DefaultTask {

                @OutputFile
                abstract RegularFileProperty getOutputFile()

                @TaskAction
                def consume() {
                    outputFile.get().asFile.write('42')
                }
            }

        task.options.generatedSourceOutputDirectory.asFile.orNull == new File(project.buildDir, 'generated/sources/annotationProcessor/java/main')
        task.options.annotationProcessorGeneratedSourcesDirectory == task.options.generatedSourceOutputDirectory.asFile.orNull
        task.options.headerOutputDirectory.asFile.orNull == new File(project.buildDir, 'generated/sources/headers/java/main')

    abstract val optionalProjects: ListProperty<String>

    @get:Internal
    abstract val projectDependencies: ConfigurableFileCollection

    @Input
    val runtime = externalDependencies.elements.map { it.map { it.asFile.name }.sorted() }

    @get:Internal
    abstract val externalDependencies: ConfigurableFileCollection

    @Input
    val projects = projectDependencies.elements.map { it.map { it.toGradleModuleName() }.sorted() }

 */
fun FileSystemOperations.removeOldVersionsFromDir(dir: Directory, shouldDelete: Spec<GradleVersion>, dirPrefix: String = "", dirSuffix: String = "") {
    if (dir.asFile.isDirectory) {
        for (cacheDir in dir.asFile.listFiles()) {
            val cacheDirName = cacheDir.name
            if (!cacheDirName.startsWith(dirPrefix) || !cacheDirName.endsWith(dirSuffix)) {
                continue
            }

                def root = layout.projectDirectory.asFile
                fc.filter { File f ->
                    f.isDirectory()
                }.elements.map {
                    it.collect { fileSystemLocation ->
                        projectDir.dir(fileSystemLocation.asFile.absolutePath)
                    }
                }
            }

                File testFile = layout.buildDirectory.file(name).get().asFile
                execOperations.javaexec {
                    assert !(it instanceof ExtensionAware)
                    it.classpath(execClasspath)
                    it.mainClass = 'org.gradle.TestMain'
                    it.args layout.projectDirectory.asFile, testFile
                }
                assert testFile.exists()
            ''')