Property<String> getMessage()
}
// end::extension[]

// Add the 'greeting' extension object to project
def extension = project.extensions.create("greeting", GreetingPluginExtension)
// end::create-extension[]

// Set a default value for 'message'
extension.message.convention("Hello from Gradle")
// end::convention[]

// Create a greeting task
abstract class GreetingTask extends DefaultTask {
    @Input

    val message: Property<String>
}
// end::extension[]

// Add the 'greeting' extension object to project
val extension = project.extensions.create<GreetingPluginExtension>("greeting")
// end::create-extension[]

// Set a default value for 'message'
extension.message.convention("Hello from Gradle")
// end::convention[]

// Create a greeting task
abstract class GreetingTask : DefaultTask() {
    @Input

====
include::sample[dir="snippets/plugins/greeting/kotlin", files="buildSrc/src/main/kotlin/greetings.gradle.kts[tags=update]"]
include::sample[dir="snippets/plugins/greeting/groovy", files="buildSrc/src/main/groovy/greetings.gradle[tags=update]"]
====

If you apply the `greetings` plugin, you can set the convention in your build script:

====
include::sample[dir="snippets/plugins/greeting/kotlin", files="app/build.gradle.kts[]"]

        german
    }
    components {
        greetings(NativeLibrarySpec) {
            binaries.all {
                if (!org.gradle.internal.os.OperatingSystem.current().isWindows()) {
                    cppCompiler.args("-fPIC");
                }
            }
        }
        hello(NativeLibrarySpec) {
            binaries.all {
                lib library: 'greetings', linkage: 'static'
            }
        }

            #include <iostream>
            #include "hello.h"
            #include "greetings.h"

            void DLL_FUNC sayHello() {
                std::cout << getHello();
            }
        """)
    ]

    SourceFile getGreetingsHeader() {
        sourceFile("headers", "greetings.h", """
            #include <string>

            #ifdef _WIN32

    def setup() {
        settingsFile << "rootProject.name = 'test'"

        buildFile << '''
            apply plugin: "cpp"
            model {
                components {
                    greetings(NativeLibrarySpec) {
                        binaries.all {
                            if (!org.gradle.internal.os.OperatingSystem.current().isWindows()) {
                                cppCompiler.args("-fPIC");

    @get:Input
    abstract val greeting: Property<String>

    init {
        greeting.convention("hello from GreetingTask")
    }

    @TaskAction
    fun greet() {
        println(greeting.get())
    }
}

// Use the default greeting
tasks.register<GreetingTask>("hello")

// Customize the greeting
tasks.register<GreetingTask>("greeting") {
    greeting = "greetings from GreetingTask"
}

                        ${name}Hello(NativeLibrarySpec) {
                            sources {
                                cpp.lib library: '${name}Greetings', linkage: 'static'
                            }
                        }
                        ${name}Greetings(NativeLibrarySpec) {
                            sources {
                                cpp.lib library: '${name}Hello', linkage: 'api'

    GreetingTask() {
        greeting.convention('hello from GreetingTask')
    }

    @TaskAction
    def greet() {
        println greeting.get()
    }
}

// Use the default greeting
tasks.register('hello', GreetingTask)

// Customize the greeting
tasks.register('greeting',GreetingTask) {
    greeting = 'greetings from GreetingTask'
}

import org.gradle.tooling.provider.model.ToolingModelBuilder
import javax.inject.Inject

apply plugin: CustomPlugin

class CustomModel implements Serializable {
    String getValue() { 'greetings' }
    Set<CustomThing> getThings() { return [new CustomThing()] }
    Map<String, CustomThing> getThingsByName() { return [thing: new CustomThing()] }
}
class CustomThing implements Serializable {
}