import org.gradle.api.Project;
import org.gradle.api.Plugin;

public class GreetingPlugin implements Plugin<Project> {

    @Override
    public void apply(Project target) {
        target.getTasks().register("hello", GreetingTask.class);
    }

import org.gradle.api.Project;
import org.gradle.api.Plugin;

public class GreetingPlugin implements Plugin<Project> {

    @Override
    public void apply(Project target) {
        target.getTasks().register("hello", GreetingTask.class);
    }

import org.gradle.api.Project;
import org.gradle.api.Plugin;

public class GreetingPlugin implements Plugin<Project> {

    @Override
    public void apply(Project target) {
        target.getTasks().register("hello", GreetingTask.class);
    }

:my-greeting-app:greeting
Hi Bob!!!
----

== Plugin changes can be tested

This sample can be used to demonstrate the development lifecycle of a Gradle plugin. Edit the file `greeting-plugin/src/main/java/org/sample/GreetingTask.java` to change the greeting, and re-execute the consumer build:

[listing.terminal]
----
> gradle --include-build ../greeting-plugin greeting

Using an extension and mapping it to a custom task's input/output properties is common in plugins.

In this example, the message property of the `GreetingPluginExtension` is mapped to the message property of the `GreetingTask` as an input:

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