implementation-class=org.gradle.api.internal.plugins.CustomPlugin...

                String getValue() {
                    return "myValue";
                }
            }

            class CustomPlugin implements Plugin<Project> {
                @Inject
                CustomPlugin(ToolingModelBuilderRegistry registry) {
                    registry.register(new CustomBuilder());
                    registry.register(new CustomBuilder2());
                }

        return modelName == '${CustomModel.name}'
    }
    Object buildAll(String modelName, Project project) {
        return new CustomModel(50)
    }
}

class CustomPlugin implements Plugin<Project> {
    @Inject
    CustomPlugin(ToolingModelBuilderRegistry registry) {
        registry.register(new CustomBuilder())
    }

    public void apply(Project project) {
    }
}
"""
        withBuildScriptIn("a")

plugins {
    id("java-gradle-plugin")
}

group = "org.sample"
version = "1.0-SNAPSHOT"

gradlePlugin {
    plugins {
        create("customPlugin") {
            id = "org.sample.greeting"
            implementationClass = "org.sample.GreetingPlugin"
        }
    }

plugins {
    id 'java-gradle-plugin'
    id 'idea'
}

group = 'org.sample'
version = '1.0-SNAPSHOT'

gradlePlugin {
    plugins {
        customPlugin {
            id = 'org.sample.greeting'
            implementationClass = 'org.sample.GreetingPlugin'
        }
    }

implementation-class: org.gradle.sample.plugin.CustomPlugin...

====
include::sample[dir="snippets/customPlugins/customPlugin/kotlin",files="build.gradle.kts[tag=no-script-plugin]"]
include::sample[dir="snippets/customPlugins/customPlugin/groovy",files="build.gradle[tag=no-script-plugin]"]
====

----
$ gradle -q hello
include::{snippetsPath}/customPlugins/customPlugin/tests/customPlugin.out[]
----

			if customPlugin, ok := enabledCustomPlugins[defaultEnabledPlugin.Name]; ok {
				logger.Info("Default plugin is explicitly re-configured; overriding", "plugin", defaultEnabledPlugin.Name)
				// Update the default plugin in place to preserve order.
				defaultEnabledPlugin = customPlugin.plugin
				replacedPluginIndex.Insert(customPlugin.index)
			}

        project.gradle.gradleUserHomeDir == project.file('userHome')
    }

    def canApplyACustomPluginUsingClass() {
        when:
        def project = buildProject()
        project.apply plugin: CustomPlugin

        then:
        project.tasks.hello instanceof DefaultTask
    }

    def canApplyACustomPluginById() {
        when:
        def project = buildProject()

            interface CustomParameter {
                void setTasks(List<String> tasks);
                List<String> getTasks();
            }

            class CustomPlugin implements Plugin<Project> {
                @Inject
                CustomPlugin(ToolingModelBuilderRegistry registry) {
                    registry.register(new CustomBuilder());
                }

                public void apply(Project project) {