class GreetingPlugin implements Plugin<Project> {
    void apply(Project project) {
        project.task(‘hello‘) {
            doLast {
                println ‘Hello from the GreetingPlugin‘
            }
        }
    }
}
apply plugin: GreetingPlugin

class GreetingPluginExtension {
    String message
    String greeter
}

class GreetingPlugin implements Plugin<Project> {
    void apply(Project project) {
        def extension = project.extensions.create(‘greeting‘, GreetingPluginExtension)
        project.task(‘hello‘) {
            doLast {
                println "${extension.message} from ${extension.greeter}"
            }
        }
    }
}
apply plugin: GreetingPlugin

greeting {
    message = ‘Hello‘
    greeter = ‘huhx‘
}

class GreetingToFileTask extends DefaultTask {

    def destination

    File getDestination() {
        project.file(destination)
    }

    @TaskAction
    def greet() {
        def file = getDestination()
        file.parentFile.mkdirs()
        file.write ‘Hello!‘
    }
}

task greet(type: GreetingToFileTask) {
    destination = { project.greetingFile }
}

task sayGreeting(dependsOn: greet) {
    doLast {
        println file(greetingFile).text
    }
}

ext.greetingFile = "$buildDir/hello.txt"

class GreetingPlugin implements Plugin<Project> {
    void apply(Project project) {
        def extension = project.extensions.create(‘greeting‘, GreetingPluginExtension, project)
        project.tasks.create(‘hello‘, Greeting) {
            message = extension.message
            outputFiles = extension.outputFiles
        }
    }
}

class GreetingPluginExtension {
    final Property<String> message
    final ConfigurableFileCollection outputFiles

    GreetingPluginExtension(Project project) {
        message = project.objects.property(String)
        message.set(‘Hello from GreetingPlugin‘)
        outputFiles = project.layout.configurableFiles()
    }

    void setOutputFiles(FileCollection outputFiles) {
        this.outputFiles.setFrom(outputFiles)
    }
}

class Greeting extends DefaultTask {
    final Property<String> message = project.objects.property(String)
    final ConfigurableFileCollection outputFiles = project.layout.configurableFiles()

    void setOutputFiles(FileCollection outputFiles) {
        this.outputFiles.setFrom(outputFiles)
    }

    @TaskAction
    void printMessage() {
        outputFiles.each {
            logger.quiet "Writing message ‘Hi from Gradle‘ to file"
            it.text = message.get()
        }
    }
}

apply plugin: GreetingPlugin

greeting {
    message = ‘Hi from Gradle‘
    outputFiles = layout.files(‘a.txt‘, ‘b.txt‘)
}